>I could voluntarily commit X additional dollars per month to be directly distributed to the creators I watch according to their share of my total watchtime, with some kind of manual opt-out button for individual videos/creators that I explicitly do not want to support.

They halfway do this. The numbers are opaque but part of your premium is given to creators you watch, and that cut is based on your watch time, among other factors.

ofc I dobut we'd ever get that granular a control on CC's. As said in another reply, memberships are sort of that solution.