For those of us who develop apps or app-sy games this is the main limiation of Construct:
it is not well suited for developing user interfaces.
Whereas Construct excels at game creation, game logic etc., a lot of game staples such as popup boxes, scrollable menus, inventories etc. usually require clever "making it work" via various things that are not normally designed for this purpose.
For example, most of what I create involves some sort of a scrollable panel, be it a level list or a menu, and it's always a pain in the butt to set it up; pinning stuff together, clamping, easing, including invisible objects and whatnot. I understand that in classic programming this sort of stuff may involve even more intricate tinkering but considering how easy and straightforward it is, for example, to have a platformer sprite, it's a bit of a cognitive dissonance.
Also basic non-game-y elements such as text, textboxes, checkboxes etc. behave their own way since they use the standard HTMl5 controls (e.g. they float over the canvas so you can't cover them with anything). A dream come true would be if all these were rewritten as "native" C3 objects but I assume that would be a whole new undertaking that would also take some focus away from what's most important.
Still I surely wouldn't be averse to some more Ui related features/facilities/tools (the frickin scrollviews!).