"one simple principle: make good products and charge money for them." Thank you for the one-time purchase option. It's a win already on today's software world.
I just looked at two pomodoro apps on the app store, one had a one-time purchase fee, the other had a subscription only model. It's a freaking pomodoro app! I can't believe I have to pay for that in the first place (why doesn't the countdown app of Apple not have a widget =.=) but a subscription? People are greedy af.
Personally, for smaller developers, I attribute this more to ignorance than malice (greed). Pricing is hard so they just look around and pick what they see happening around them without taking a moment even to think, forget about doing actual research.