Several things:
1) I'm very impressed with everyone's karmal knowledge on here;
2) Negative TPs are gone for good;
3) We don't have the option of allowing TPs to be given on the front page or in chat, although I agree it's a good idea;
4) Admins have the option of adjusting the number of "karma actions" per hour;
5) The staff isn't inclined to change the current standard. There are several reasons, among them:
a) currently, everyone's TPs are "worth" the same thing, meaning they got them under the same rules. Changing the rules means that the contributions of members who earned their TPs under the earlier system would be devalued;
b) With all the various dramas we've had with TPs in the past, I see no reason to add to that by adding different levels of TPs. If posters could give 3 TPs, they would. Some posters would potentially give their friends 3 TPs for a good post, but other members only 1 TP, leading people to ask why their post wasn't worth as much.
c) The current system works relatively fine. If people want to give TPs for multiple posts made within an hour of one another, they can make it up to them in an hour or two.