MIRI stated goals are similar to those of mainstream AI research, and MIRI approach in particular includes as subgoals the goals of research fields such as model checking and automated theorem proving.

It's definitely not a goal of mainstream AI, and not even a goal of most AGI researchers, to create self-modifying AI that provably preserves its goals. MIRI's work on this topic doesn't seem relevant to what mainstream AI researchers want to achieve.

Zooming out from MIRI's technical work to MIRI's general mission, it's certainly true that MIRI's failure to convince the AI world of the importance of preventing unFriendly AI is Bayesian evidence against MIRI's perspective being correct. Personally, I don't find this evidence strong enough to make me think that preventing unFriendly AI isn't worth working on.

Also, two more points why MIRI isn't that likely to produce research AI researchers will see as a direct boon to their field: One, stuff that's close to something people are already trying to do is more often already worked on; the stuff that people aren't working on seem more important for MIRI to work on. And two, AGI researchers in particular are particularly interested in results that get us closer to AGI, and MIRI is trying to work on topics that can be published about without bringing the world closer to AGI.