The customers are then stuck with an app that might have been good but decays over time.
The real problem is that we just don't need 80 gazillion apps. The "app" market is extremely competitive, that's really what people are complaining about, profits have been driven down to basically nothing. Normally you would expect some developers to drop out of the market, which would help the situation, but two things are stopping that from happening, in my opinion.
First, the platform companies (Apple and Google) have been incredibly successful at promoting app development as a gold mine. For every developer who gets sick of it and moves on to something else, two people become "app developers".
Second, there's a startup bubble and the wisdom out there says you need an app or your startup is nothing. This partly relates to the first point, the hype around "apps", even years after Apple launched the app store, is deafening.
Or the reverse, pay $100 to pull your app from the store after its first year.
I almost think devs would be better off if it was per app. At least any devs planning to make a living off the store. It would cut down on a lot of the crappy spammy apps out there.