You are making a lot of good points here!
I agree with you that there will always be some users running projects that do not rain GRC. However, if the number of users starts to increase by, lets say, 10 fold, there will be more and more people crunching for the sole purpose of acquiring GRC. This would then cause an imbalance between the projects, as I mentioned in another post already.
I really don't have an idea how this problem could be solved. I thought about it for almost 2 days now and my limited mind can't solve it yet.