It is known since... forever?, that one should not speculate across security boundaries. This was not enough to avoid Spectre, but this was largely enough to avoid TONS of security vulns Intel is also susceptible to.

Somebody messed-up big time. Or from a business point of view did they? Intel current problems are manufacturing and the continuously lower power of their "legacy" processor (except due to manufacturing problems, this "legacy" is still mostly the current one) makes it so that people are buying more. Of course there is AMD back in the game, but the market demand is large enough; plus AMD would have been there anyway, and, in the fiction that Intel did take good parts of the perf hit upfront instead of the secu vulns, as competitive as in the current situation.

The people most annoyed are the users. Intel got away by pretending this was not really defects in their product but only new SW tricks that they will help defend against, and their clients just let them say that without much complaint (well, I guess big ones got some rebate...) but security researchers and/or processor designers know very well this is bullshit (see the vulns papers and FAQ) and that they simply fucked-up big time on Meltdown, MDS, etc. I don't care that a few other vendors did some of the same mistakes: they are still mistakes and design flaws, and not even something new.

Pretty much the only new shinny thing in this stream of vulns was Spectre and the few variants that appeared quite early on (but NOT Meltdown&co). The rest are design flaws that comes from the "oh not a big deal to leak that potentially privileged data, we will drop anything and trap before any derivative can go out anyway" mentality. Yeah, no, I'm sorry but the funding paper about speculation already told to not do that :/ Either they did not do their homework, or they voluntarily chose to violate the rule.