I really appreciated informational value of both posts, especially the effort you put into interviewing tool makers.
My experience comes from designing complex desktop applications (imagine 3D Studio but for Structural Design) through web to on-premise enterprise apps. The problem solving approach is the same, but the process and tools are quite different. With all your feature suggestions you are targeting web & mobile, but there is also world of native desktop and on-premise apps. Guys designing 3D Studio needs some toolkit too ;)
Suggestions for my “Real UX Tool” are mostly inline with Stephen from InVision:
My ideal UX tool is not massive monster that is attempting to solve it all, but a toolbelt. My ideal tool consists of bundles, whose outputs can be linked together to maintain design integrity. I would like to choose different vendors for each bundle and let them compete to bring me the best features. I need different “Prototype validation bundle" for web, desktop, mobile or enterprise, customer, kids app. I need to integrate existing "Communication bundle" (Yammer, Slack, Wiki) for design feedback, not force people to use another tool that does the same.
My current real UX tool is internal Wiki :)