I think the logic behind the SP being enforced is to maintain money within the system, so that users are incentivised to build SP and can't just post and run. There are a variety of benefits to having SP as part of the payout. I personally think that scrapping SBD entirely is a good idea and then we can just get paid in SP and liquid steem - eliminating a lot of confusion. If SBD can be reliably pegged to USD then that changes things, but all current signs suggest it won't be easy to achieve that.
I'm a fan of simplicity and having 3 forms of currency is a bit overkill I think. In any case, I have no plan to push for any particular change currently... We have more pressing things to fix that aren't being fixed!
We are already pretty incentivized to have money in the system with the long power-down period.
I was also for scrapping SBD before, but I have changed somewhat and I believe payout should be in SBD, as kind of a dividend for holding Steem Power. Then it is easier to value the Steem blockchain also with traditional financial metrics. But, I agree with you: More pressing things to fix.