Making it on the App store with games is extremely hard.
I have 3 friends who each developed a mobile game and made no money, basically the games serve as portfolio for future work.
I don't think the quality is the issue with what my friends produced:
how would you differentiate them with marketing? "yet another color bubble popper!" "yet another side-scrolling shooter where you kill the undead!" "yet another match three with fruit!"
i'm not sure i agree with your assessment as to marketing failures. if you said me-too-market-fit, however, i'd say you were on to something.
their level of polish is pretty nice, so they should step out of the lottery and make a non-me-too quality game. i bet they would be pretty successful with it. in fact, if they keep with it, i'd put money on it they'll eventually be very successful.
I hope you are right - that a fun new gameplay with an adequate level of polish is enough for moderate success.
I guess that deep down I also believe the same and that is what makes me keep on going to finish my side project.
It's a game I have been working on for some time. The gameplay is simple and easy to copy and that is why I have been reluctant to show it to too many people.
I hope to finish it in the next 6 months but It could take longer depending on how much spare time I have for it.
I am planning on showing it to the HN crowd first - the support is always pretty good here.
http://www.whitebat.co.uk/fruitfrenzy/
http://gamewhizzes.com/
http://ludimate.com/x-rainbow/index.php
Most likely marketing failures.
That being said, I am working on one myself and have all the hopes that any indie has.