For every person who knows what they're doing and can trust themselves, there are 1000 who will install malware and other crap and end up at an Apple store getting it fixed, and they'll blame Apple instead of themselves.
If your engine fails because you drove it into a river, then the warranty don't cover it and you'll pay out of pocket for repairs.
I feel like I have to be misunderstanding you because that makes no sense.
While I may not always agree with Apple's approach I can understand their reasoning and don't believe that it simply comes down to earning a few extra bucks with the 30% cut in question and all the seemingly drastic measures that come with it.
Most users do not want this, but some do.
Some users will consider a RAT a way to fix things, while others will consider some game to be a malicious drug. Both should be allowed to make their own decisions if they really want to.
And, now that I think about it, I don't even know what the equivalent of "driving into a river" would be, and that's as a software engineer who's been working with computers for 25 years.