I think a part of the problem is, f.lux was and still is developed and designed by only 2 people: Michael and Lorna. They are "the f.lux team". Another problem I see is, they don't really do any public beta testing nor do they have a big team of people doing private beta testing. They just make it as they see fit and then release it and hope for the best.
Always remember that they are doing this for free. They aren't getting financially compensated for it at all - at least not for f.lux or the time they put into it. This is a project of passion.