I agree with you that the cart seems to be moving ahead of the horse, in that there is an increasing fixation on the theoretical status of the encryption scheme rather than the practical risk of various outcomes. An important facet of this is that systems that attempt to be too secure will prevent users from reading their own messages and hence will induce those users to use "less secure" systems. (This has been a problem on Matrix, where clients have often not clearly communicated to users that logging out can result in permanently missed messages.)

There's a part of me that wonders whether some of the more hardcore desiderata like perfect forward secrecy are, in practical terms, incompatible with what users want from messaging. What users want is "I can see all of my own messages whenever I want to and no one else can ever see any of them." This is very hard to achieve. There is a fundamental tension between "security" and things like password resets or "lost my phone" recovery.

I think if people fully understood the full range of possible outcomes, a fair number wouldn't actually want the strongest E2EE protection. Rather, what they want are promises on a different plane, such as ironclad legal guarantees (an extreme example being something like "if someone else looks at my messages they will go to jail for life"). People who want the highest level of technical security may have different priorities, but designing the systems for those priorities risks a backlash from users who aren't willing to accept those tradeoffs.