The 7 day limit and all the rest of it is due to technical limitations for sure. It all comes down to anonymity and spam prevention etc. At some point, I think we might need to make major changes to the chain or node system in order to close these security holes and be able to expand on more sustainable grounds.

However, these ideas that you mention would be ripe for testing with the new SMTs. Basically, all sorts of features could be implemented as opt-in, either entirely or to be required on particular Steem apps/sites. That way we can "simulate" another token used to reward blogging/verification and either keep the simulation, or make it a permanent feature of Steem itself at some point.