This is true, though it is possible for phones to check the certificate online at install time, so the app could potentially only affect phones up until the cer

This is true, though it is possible for phones to check the certificate online at install time, so the app could potentially only affect phones up until the certificate is revoked then no more. Also, I had to go through a number of hoops to get the certificate in the first place - proving that I was a registered company, handing over a chunk of cash etc. That has to be pretty off putting for a malicious coder. Its even simpler with an app store model: if the app misbehaves or is misleading then it can be downvoted or even removed.