I wonder if more apps will go for, say 50¢, instead of free + $1.00 IAP. I miss the pre-IAP days.
The old desktop approach of new major versions that people have to purchase periodically is not really feasible on IOS, since old versions would clog up the app store, and there is no way to offer the new versions at a discount to past purchasers, which desktop software likes to do to avoid annoying recent customers when a new version comes out.
So to recover for costs from ongoing development, an app developer will either need to 1) somehow increase the number of people who will purchase the app, 2) add a recurring revenue source like ads to the app (possibly with IAP to disable), 3) make the app subscription based (but only some types of apps can pull this off), or 4) make the app IAP based, and when updating add new features that can be purchased.
Now not every app does any of those. Some will just a single unlock IAP with limited functionality before that. But this is not all that different from the old demo or shareware approach, and the design of the app store makes it generally better to have the demo and full version be the same app, at which point IAP is the way to do that. Without a recurring revenue source though, such apps are likely to either change approach or get abandoned eventually once the costs of periodically upgrading the app exceed the remaining revenue coming in.
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Also there is the abusive IAP single use item to bypass artificial cooldowns MTX garbage that mobile games tend to be full of, but I really cannot bring myself to accept that as a legitimate business model. Even the Gacha model (terrible as it is) feels somewhat more legitimate, but I have plenty of significant concerns about those too. But I'm really looking at this from the perspective of non-games, or at least not "F2P" games.