All of the crapware on my Android phone comes from companies approved by Google. In fact, most of it... ahem... comes from Google. Blimely... I forbid Google maps from even running.... Literally every app I use comes from Fdroid and you wouldn't believe how much better the phone runs.
The walled garden is not so much a walled garden as a zoo. You are a valued guest as long as you provide value to the proprietors. You get lovely meals and safe-ish surroundings. The fact that your pen is completely inappropriate for your body type... Well, you can't have everything, right? But the paying customers are the ones making the rules and you shouldn't forget it.
Yeah, I don't think you'll get many Madagascar type prison breaks from the walled garden, as you say, but I think it's a stretch to say that there is nothing to gain from doing so -- whoever you are.