Changing the total supply from 1B to something else would be a lot more controversial than reducing the fees - effectively that amount was a "promise" made at the outset so if that promise were to be broken I would expect some investors (especially the 73 initial ones) would be unhappy about that (actually it would probably upset those who have invested at recent "market prices" much more than the 73 as they have already probably each taken large profits from their initial investment).