Your point of view as a developer is valid and I totally support being paid for one's work.
The point of jailbreaking is not, however, just cheating on app payments. It can also very much be getting rid of preinstalled crap that your operator foists on you without asking for your opinion on the matter.
I do not jailbreak my phone as a matter of principle. I do get pissed off every time I see yet another update for Google Play or whatever other piece of crap thing they want to update, instead of letting me use my bandwidth as I see fit.
Of course, I am rather laughing at the moment because, after almost 3 years of use, the available space for downloads is now insufficient for the crap updates to load. The only problem is that I can't get the other updates I need either.
So it's a clusterfuck, basically, and it demonstrates that nobody in that food chain has given a moment of thought to the problem because everyone expects consumers to change their phone as soon as the new shiny comes out.
If I jailbreak my phone, then I can get rid of all the crapware I don't want and keep my phone storage space for the stuff I actually need.
But I still won't do that, because the risk of exposure to malware by simply being jailbroken is too great.
Seems I'm gonna have to give thought to replacing that phone after all.