Hum, if I got the initial post right, that was the very point made here. If we would want to have developers to invest in original ideas in a market that has so little barriers, it's probably up to the customers (and their long term strategy) to care for this. Otherwise, it wouldn't be wise for anyone to invest in this market place at all, which would probably effect in a total lack of originality in the goods traded there.

Edit: Please note that it is in the very nature of a game (being it a mobile game or a board game) to have quite simple mechanics and a limited set of rules, in a sense of "simple to learn, impossible to master" (as mentioned by the authors of Threes!). So it's in the very essence of a good game to allow copies with an effort that is in no relation with the effort that has to be invested to come up with the rules and mechanics in the first place.