Actually, I believe we want to encourage community based grants for these funds, it would encourage adoption of the coin by allowing communities of miners to compete with each other for a chunk of the grant. If you also include a maximum amount of the total grant a single proposal can capture (say 20%), then once a grant hits 20%, people no longer have any need to put more of their limited votes to it, and if they do, they're effectively wasted.
While there's always the possibility that these "interest fund" grants would grow to capture more than one individual grant once the first hits 20%, it's incredibly unlikely that this would ever cause you or MCF to actually lose your grant. If you also allow more than 5 grants (maybe not unlimited, but a lot, in this sense I agree with the 100 grants idea), then you may not get a full 20% of the grant coins, but however much you do receive would fully be a reflection of the mining community's perception of how well you're doing as a developer. Additionally, even if these interest funds captured 80% of the grants in total, that would simply be an indication of the community mindset in general, and if the mindset is truly that greedy overall, it's very likely that those interest funds will eventually capture your single grant in the planned fork. The bottom line is that as long as you let people vote on where free money goes, there will be a certain percentage that will always vote for it to go to themselves.
As for the potential of having a voted on regulator to approve grant proposals, I believe it would be detrimental in that the regulator would inevitably make a decision that upset some people, and these people would rally/rage/abandon the coin. If this were to happen to a large enough extent, or if a malicious group managed to gain control of this regulatory position it could effectively kill the coin by giving them too much control. If, instead, you allow your users to directly control approval of grant proposals before they're even voted to be funded, the only blame for a bad decision is on the community itself, and people tend to get less angry when they're the one making the decisions, even if they're stupid decisions that backfire.