I think the idea of simplicity is still relevant, but the problem is not as simple as (no pun) having a certain look to your ISA anymore. ISA transformed to something unrecognisable 2-3 steps into the pipeline, the rest of the CPU doesn't see much of the ISA.
Maybey we should abandon "reduced instruction set" and instead evaluate how ISA is suitable for out of order execution or speculative execution or backtracking and so on
Fair. Personally, I think the idea of simplicity is still relevant for pedagogy (as it always is), but one you rope in 'suitable for out of order execution or speculative execution or backtracking and so on' as criteria, 'simple' is harder to achieve (at least for practical commercial designs). YMMV.