Hey, I tried to leave a comment reply on Retromation's video, but Youtube seems to have shadowbanned it (I can't see it from another browser). So here's what it was (and what about it would be an issue, I have no idea):
I think for some abilities (like reroll piece), having 2-3 charges could help a lot, so things can be used when they're useful, with less pressure to use it to get it on cooldown so it can be cooling down. If you have a charge, but one is cooling down, you can safely save it and use it when it fits the situation, rather than feeling like you're wasting potential.
Also if you haven't (maybe you have?), check SNES's "Tetris Battle Gaiden", maybe some ideas or inspiration for more abilities in there.
(I might also say you could only get 1 charge at a time, not get a full stack from one good move, but not sure about it, just an idea. As in, you have 0 charges, it at most fills up the one and doesn't give progress on the next, mostly to preserve any current balancing, but also because it kind of undoes the intended effect of having less pressure (if you can get multiple at once), making it so you'd want to use everything up so you get all your potential charging if you get a good move in. I think I talked myself into liking that idea more, lol.)