I never understood why in-app purchases have been branded as "evil" in the first place. As long as Apple doesn't offer developers a way to do trials, it's the closest way a customer can get a taste of an app's features, esthetics before deciding whether to pay or not for an app. EX : I wouldn't have paid 10$ for flighttrack pro without the in app purchase option. I would go as far as theorize that the main reason why…
I much prefer the "Lite" model, where you basically have a functional demo for free, then a separate paid app. Offer the paid features in the "Lite" version as an IAP too, if you think that helps.
What it comes down to is that a good transaction should be a net gain for both sides. I give you money, and in exchange I get something that's worth more to me than the money I give you. We both win! But the way many of these games are done, the creator deliberately makes their game less fun in order to make it more lucrative. It's no longer mutually beneficial. Rather than adding value to get more money from me, they actually reduce value to try to extract more cash.