With the way the UI works now, the user doesn't have the permissions to delete the built-in apps (only root does). Giving the user permission to do this can be detrimental to the OS as a whole (giving the user root), or will still potentially leave the user in a bad state really easily if the user is only given permission to edit the apps. That's problem #2.
What are you talking about?
Just go to SETTINGS - GENERAL - RESTRICTIONS
Turn off the camera. Look, the camera is gone! I'm not sure what all the technical problems you're talking about really mean, but it doesn't stop me from removing the camera or Youtube if I want to.
Why can't they just put 'Stocks' or 'Weather' on that list? Easy. Done.