I certainly wouldn’t mind better mixing tools, but I just don’t need a full DAW attached to my NLE. Others might. I could see maybe a different project type with a ‘mix’ icon, where you get a different interface with faders, channel config, sends, etc. If round-tripping wasn’t such a crapshoot, that alone would be a big improvement.
I still view FCPX in a sort of ‘camera body’ context, where I can build or buy the options I need.
Project consolidation tools are quite another story – Ol’ #7 had pretty good options that I still miss.
Another thing that would help a lot would be comprehensive info in the inspector explaining why that stupid yellow triangle is on my timeline icon in the browser.