I work for a few clients designing military-style patches, which often necessitates curved text. I find the current system of having to juggle with a bunch of little red flags until I manage to get the text in the right place on a shape and all on the same line a very cumbersome in experience.
What I think would be a much smoother system:
-On closed shapes (eg, a circle or custom shapes) have a button in the top tool-bar to swap the text from inside to outside the shape rather than trying to manhandle flags. Perhaps another button to give your the old view if you want that extra control?
-Some form of flag which allowed you to set a 'centre' point on the shape, which you can justify the text to, allowing things to be easily kept symmetrical. When designing patches, I often get client requests to make the text bigger/smaller or have the copy changed slightly, which then requires effort realigning everything. This 'can' be done with the current system, but it doesn't make it easy.
I understand this isn't a priority at all, and my needs are fairly niche, but I thought I'd mention it anyway since it's one of the VERY few gripes I have with AD!