I've suggested in the past that we remove signature sizes from rank completely and people can just donate to get a Senior or Hero-sized signature etc (along with some other perks).
I would generally support this kind of proposal. One drawback however would be that it would add some level of controversy to banning users because doing so would take away features that someone has paid for. It would also be difficult to price because of the large variance in income and wealth throughout the world. Another issue is that users will sometimes use their signature to protest certain actions and/or policies and this proposal would make that more difficult/costly.
I do think you are on the right track though. Maybe instead of outright disabling signatures for low ranking users, the size/features of low ranking signatures could be severely limited except when a donation is made.
Another solution could be to, by default only allow say 10 activity to accure every two weeks however if someone donates then 14 activity would accure every two weeks starting the activity period after the donation. Activity requirements would remain constant. (The specifics can be adjusted if desired).
