I think you've hit on a big part of it. It seems Apple works more closely with their iOS developers than Amazon does with their Android developers. The Fire OS itself is very nice, fluid, responsive, and makes sense when you treat it as a purely consumption oriented device. That's why it's such a shame that third party apps and games can look awkward on the larger tablet; the user experience should matter more but it seems Amazon doesn't want to put in the same effort to support their third party developers.