Having a credit card on file is neither a necessary, nor a sufficient condition to have a better app ecosystem. But if you had two app ecosystems that were identical aside from the fact that one stored credit cards and the other did not, you would certainly expect a better app ecosystem with the stored cards. Having to enter your credit card is a source of additional friction that decreases people's purchase rates of apps, even if by a small amount (although my opinion is that it's by a large amount). Having an app ecosystem where people spend money and spend it more freely certainly seems to improve the ecosystem, if you take comparisons between the iPhone and Android app stores into account, especially in the earlier days.