I think their new refund policy will also help a lot. Being able to try a game to see if it works, and get your money back hassle-free if it doesn't, ought to take a lot of the anxiety out of the fragmented-target-OS issue.
Sure, the refund happens but now the devs have to contend with all the pissy reviews on their game's store page because the game didn't work with their very specific use cases. Its easier to just not bother unless you want to devote significant support and development resources to making the game run on any linux frakenputer.
