What is more inspiring than money as far as miners are concerned?  Nothing is, mining pools want nothing more than to include as many transactions as possible, when they mine an empty block or one with just a few transactions it happens for a reason, also many people seem to think that there is a centralized mempool the all miners share, there isn't, I can just claim that "my" mempool is empty and mine only empty blocks.

This is a free market, subject to spam and biding, exactly how a decentralized system should be, there is nothing you can do to make it better.