Yes, I am aware of this method, but it is very restricting, it only affects stuff that exist on the same layer, or on layers that are stacked together. What I am asking is vastly more powerful, because you could use any sprite to cutout (or mask in) any other sprite on any other layer! Multiple sprites/layers included! Now, the only way to achieve something like this is to have multiple sprites everywhere. And the applications graphic-wise are many, to name a few: decals (from explosion burns to blood stains), reflections, shadows that affect some parts of the image and can be controlled from the mask to reflect z-order changes etc...
eli0s: items 2, 3 and 4 sound like they are already possible, 5 and 6 via existing third party addons (e.g. Spriter). It sounds like you're underestimating what's already possible.
I am sure I underestimate what is already possible, because I am not proficient with coding/programming and I can't even imagine what can be done when someone is! I have a clear idea however, every time I see a capx made by R0J0hound I stand in awe, feeling like a slightly evolved monkey!
However, my point is that most of these features should be included and be easily accessible by default. For example, I know that R0J0 can make an amazing multi-lighting system just by using his canvas plugin, but I can't, it's too convoluted for me and it shouldn't be like this. I know that pathfinding's nodes can be used to create a grid based system, but it is also somewhat complicated, even considering the fact that I was lucky enough to see lolpaca's LinearPathfinding.capx. Masking also leave a lot to be desired, as I wrote above.
As for the text, I know that rexrainbow had made behaviors that add some of those functions, but shouldn't those be already implemented by default? And I can't see how I can change part of the written text to be bold, an other color
or an other size
... Something basic if you want to emphasize some parts of a dialog for example.
Finally, I own Spriter, but as Colludium already stated, it's too time consuming and convoluted to design and work like this. I don't mind using Spriter for extremely complicated character interactions, but I would very much like to be able to move any part that exist within my scene, record this movement with keyframes, apply easing and call these animations with events, in any order, at any time, at any rate! And this, ideally, should be done and previewed within the editor!
I know, I might ask for too much, I am sure that most of those things are insanely difficult to program, never the less from my point of view, as a creator, seem essential to have!