Check out the top independently made apps in the iTunes store. Look at the Health & Fitness category, for example. You'll notice a trend: most of them are horribly designed. Just plain ugly. If branding and UX matter, than why is the top of the app charts not filled with beautiful, easy to use apps?
Because they're shitty apps crapped out in a day due to deadlines and then forcefully cross-promoted and spammed across that company's other applications, and paid placement