In spite of that, Construct games I have seen are platformers or top-view shooter/walker types.
You won't see many other genres in similar programs either. RTS games are kinda pointless unless you have online play, and imo are horrible in 2D, not to mention incredibly complicated to make. RPGs are also incredibly complicated; I've seen like...2 successful/completed RPGs made in programs like Construct. There are a few racing, puzzle, and shmup games made in Construct as well..ya just gotta look for them!
Would be fine to find original games, or of other genres like RTS, etc.
These functionalities are built in Construct, why can't we see them implemented?
There is an RTS movement behavior, sure, but you need a lot more than that to actually make an RTS game..That's not to say they aren't possible to make, just that people generally aren't willing to put so much work into a niche game.
When will CC or C2 be mature enough to use all the built-in features?
I don't understand what you mean; all of the default behaviors you get with Construct Classic are completed and ready to go. Construct 2, however..who knows :)