If the 5% fee were to be implemented, I am more inclined to support it, if it were opt-in based. And the opt-in effect should be delayed (2 weeks, 30 days?) in order to prevent someone who compromises an account to opt-in and automatically withdraw. As for the destination of the fee, I'd allow options, regarding the destination: @steem.dao, @null, maybe @steemalliance if they can take this kind of funding.
But on the long term, I prefer the solution @therealwolf proposes with differentiated interest benefits, based on the duration of committed power up. With the possibility to have different "deposits" with different interests, kinda like at the bank. That doesn't exclude the possibility of implementing both.
Both are not the kind of easy fixes Steemit expects, like changing "13" with "4". Both will require some work and some code auditing afterwards, especially since we are dealing with wallet code changes.