Stop Using the Cup of Coffee vs. $0.99 App Analogy
If I see something that is both "free" and "in-app purchases", it already greatly reduces the chance I'll even bother to download because so damned many of these are just terrible experiences.  On the off chance I bother to look one step further and preview the "top in-app purchases", I usually see something totally unsurprising like the absurd "$9.99 gem bags" or whatever.Please, please just start charging for apps again.  I specifically search for "pay once and never again" apps now.