That security argument is like advocating wearing a motorcycle helmet when walking down the street. It sounds like a great idea and super safe, but it’s also super impractical and the things it’s supposed to protect against are extremely unlikely.
But ok, more security isn’t a bad thing. But why not make it an option, like SELinux for example? That way users can choose a degree on a scale between security and convenience that suits their use case and circumstances. Why make it all or nothing?