I'm sympathetic to your argument, but the more you harp on about "free" the less sympathetic I get. Most apps aren't free: they ask me to pay with money or data, which I do, or attention, which I prefer not to. Ad supported apps are not literally free — there's an exchange of value from the user to the developer in all cases.

I suspect what lies at the heart of this whole issue is that some developers think that attention is not a cost to the user.