I hate this pseudo-cutesy zero-context crap so very, very much.
The worst part is that it's unsolicited. At least have the courtesy to ask.
There's no wrong answer; for some people the past is more painful than joyous. Personally, I'll take the occasional jarring bad to get the bountiful reminders of the good. Or maybe it's just my personality to take more pictures of happy things.
If most people like it, fine to leave it on by default I guess - the growth team has to get promoted some way. But at least let me disable it.
"You have a new memory"
Disable that crap entirely. Same goes for a lot of preinstalled apps - News, Music, Game Center (why does that one still exist?), etc.
Hopefully they'll be with me for many years to come, but of course they will eventually pass away. I take a lot of photos of them, and I know after they pass, they will show up in these "X years ago" memory slots frequently enough that I will be unable to look at theses memory things at all. It's depressing to think about. I can't imagine how people who have a spouse who has died (or, god forbid, a child who has died) deal with these sorts of unexpected, unplanned, unwelcome reminders of who they've lost.
And beyond that, I've have 10+ years of photos in there... I often see ex-partners show up. Fortunately it doesn't bother me that much, but I can imagine it could be really uncomfortable for many people.
On the flip side, I really do love the innocuous trips down memory lane this sort of thing gives me all the time. But it would be so easy to completely ruin the experience if the wrong photo shows up.
I LOVE seeing Google photos rotate in pictures of them in this type of thing. It brings back great memories and I always smile. To me, this is better than having them stashed in a printed photo album that I never look at or in Google Photos album that I never look at.
Other people also loved my dogs, and giving them a final photograph to say goodbye to helped them. I also have photographs of tax documents, graves, medical issues, and, yes, lots of fun things as well, all of which serve their purpose. No one (except for Google's AI) would think they all belong in the same bucket to pull from.
Your comment and the one you replied to can be read as "you're weird and you grieve wrong", which is extremely rude and unsymapthetic given the context. It's also entirely orthogonal to the complaint that these features should be opt-in or allow you to opt out. That complaint is entirely valid but questioning the decision to capture sad moments suggests it's not.