I think this is the wrong direction. You should give SPS more utility not less and reducing renting/delegation efficiency is reducing utility. If you want more benefit to staking, create more areas where SPS need to be staked for benefits a.k.a more utility. The reason SPS rentals are cheap is that there are tons of players who either don't need the current utility (as in don't play in ranked) or have so much SPS that they can't utilize all of it (for example being in a far too low league for their stake).

SPS stake dependency for fortune draws is a good start, land seems like an opportunity too. More utility will give value to a gaming token.