Intels X86S proposal[1] gives perspective on this. Both in how there would be reasons to get rid of legacy, and how yet it still got shot down pretty quickly[2]. It's unfortunate that I don't think we ever got more explanation on it's termination, where did the opposition come from

[1] https://news.ycombinator.com/item?id=36013257

[2] https://news.ycombinator.com/item?id=42468664