I'm not against the idea of having to invest a few bucks.
But there will always be a tradeoff, requiring to own some tokens would turn Alien Worlds into another game only a handful of people are playing and in a few years (or months) nobody would remember.
I think AW has to be accessible to the main stream (who is willing to do KYC at some unknown exchange listing WAX and invest a few bucks in WAX just to be able to press a button for a few cents). Maybe lowering the rewards for accounts not holding WAX would reduce the tradeoff

Increasing PoW difficulty would at least have no impact on user experience if the implementation is improved by the same factor