I think the problem with the kind of very-selective appreciation that I, admittedly, probably could cultivate for some small niches of math if I tried, is that it's
kinda useless for anything but a hobby-level interest having about as much value, however you like to measure it (productivity, education) as solving sudoku puzzles or any other somewhat-mentally-active pastime. Thinking Euclid's a little fun to read doesn't readily translate into feeling an urge to work through an analysis curriculum, nor create FOMO that I might reach a place of greater joy if I gritted my teeth and did it anyway, you know?
Math-fans who (and I don't fault them for this! I get it! I just think they're barking up the wrong tree) urge attempts to adjust curricula in an attempt to get students to find the kind of appreciation they have for math are hoping, I think, that it'll drive a rather broader-reaching and more productive engagement with mathematics through the rest of school resulting in much better overall understanding of math across the public, rather than to get more people to engage in casual and occasional Sunday morning stepping-through of simple geometry proofs while sipping tea, or solving a few easy diophantine problems or puzzling over a couple pages of Martin Gardner while winding down before bed. I'm sure they would be happy (or, at least, not unhappy) to see more of those latter effects, too, but I don't think that's why they advocate changes in pedagogy.
I think they want—for good reasons—to try to help students find intrinsic motivation to work up to the point that they can appreciate and enjoy higher math, and I (weakly—it's not like I've done a study on this, it's mostly impressions from talking to people over a lot of years) believe they're attempting something doomed to fail. I think they'd have better luck focusing far more on practical applications (Yuck, not even really math! Yeah, I know, I know) than traditional k-12 math instruction has, to motivate most students, and putting up less resistance to the deadly-effective (if also deadly boring) rote memorization in early grades that some in the math-lover contingent seem to especially dislike. Their fellow math-lover youngsters will mostly (I speculate) find their way to higher math and to their joy at a finely-constructed proof without much more than a little exposure to it to get them started (which parts of the curriculum the rest of the students will probably find very unpleasant, LOL)
I think (again, I very much could be wrong on this, I'm no expert) their fundamental mistake is a belief that school is somehow making students dislike math because it's not showing them the beauty of it, or because they take too long to get to proofs (you're not even really doing math until then, after all! Is a sentiment I've often read and heard) or what have you. I do believe there's a motivation problem with mathematics in school, I just think we're in an unfortunate position where most of the folks best-positioned to drive change in how we teach math have a perspective on it that's also the reason they did so well and went so far with it, and want to transfer that perspective to as many students as they can, but I just doubt there are a lot out there who didn't happen on that perspective by some combination of birth and fortune but who would acquire it if you could only present them watered-down Velleman and some toy demonstrations of integrals as second graders. I worry that's not a useful route to making the median student care at all more about math than they already do, and may (MAY! This part's an especially weak claim) displace instruction that would benefit them more.
To put it another way: students who like reading, or at the very least are motivated enough to address it with an attitude more-present than extreme reluctance and avoidance, mostly like it due to what literacy does for them. They like what it lets them accomplish ("I can understand this video game now! Hell yeah!"), they like that it unlocks the ability to enjoy stories, including maybe some that would be off-limits in visual media (the reading is just the medium, it's not like they're sitting down with joy to do reading exercises in their spare time, they're reading because they're getting something else out of it) or to communicate ordinary everyday things among their friends. You do get the kids who nerd out over language itself—these are like the natural math-lovers—but that's not the usually motivation for most students who manage to do at least OK at becoming literate.
Literacy's superpower in a school setting is that its benefits and the value of putting some effort into it are immediately apparent to any student who isn't badly deficient in it, and natural opportunities for practice accessible to young students are everywhere in normal life, with potentially dozens of well-motivated opportunities for practice per hour if you're not even trying to seek them out. Math's handicap in that same setting is that its immediate benefits are much more scattered and limited—it's a very powerful tool, but you don't need it to gossip with your friends over instant message, or to read that slightly-too-naughty-for-your-age book you managed to get ahold of, or to figure out the early puzzle that's been keeping you from getting very far in some video game you want to play, or what have you. Occasionally it's relevant to those kinds of things! Sort of! (mostly the video game example) But not so consistently as reading and writing, and when it is, it's not proofs, generally, it's basic arithmetic and maybe some light fractions or percentage work.
We don't motivate young readers to stretch themselves by going "look how fucking sublime this passage in King Lear is! Oh, oh, and look at that aptly-employed gerund over there! Oh and that pun there may have roots in this fascinating, obscure, middle-English work, which suggests that..."
No, we go, "here's this story that's for older kids, but I think maybe if you try, you can read it, and who knows what might be in there, for older kids..." (meanwhile, we know the worst thing in there's a mild dick joke, few relatively tame swear words, and an oblique reference to a sex act that they definitely won't notice unless they're already familiar with it, all of which are probably less-bad than things they've heard from their peers this week—but man, will they feel like they got to do something forbidden!)
What's the equivalent for math? For god's sake, literacy basically gets to employ all the seven deadly sins to get kids to read and write! Literacy has Satan, lord of darkness riding shotgun! Reading is metal! What is poor mathematics to do? I do not know if there is anything like that for math, but I don't think trying to get kids to appreciate the beauty of proofs or delightful symmetry in some seemingly-unrelated pair of equations is likely a productive path to explore. We wouldn't expect something similar to work in literacy—and fortunately we don't have any strong reason to try it—so I don't know why we'd expect it to work for math.
What I'd like to see is an attempt to all but completely remove math per se from the curriculum of most grades, rolling it into other subjects, including literature but especially (of course) science, to include social science, plus practical and fine arts, with most of the remaining dedicated mathematical instruction in early grades devoted to bad ol' "math facts" (memorization via drilling) and the use of those and teaching of methods occurring mainly in other subjects, to try to demonstrate utility alongside the instruction in methods. Would it work? I dunno, but I think it's worth trying. The closest thing I'm aware of (and it's only kinda close) is aimed mainly at postsecondary students, under so-called "great books" programs. I don't know whether something akin to that's been attempted in a school setting (home schooling's so very different, for a bunch of reasons) with kids as young as primary school. I'm not sure there are a lot of alternatives, aside from accepting that most of k-12 math education is going to be a widely-hated mostly-waste-of-time for the majority of students (and hell, maybe that really is just the best we can practically achieve, and we have to live with it)