After getting bug reports of users, making minor changes to functionality, and discussion with others.
- Blender is trying to make decisions for the user, this is OK as an opt-in for users who like, but I think we shouldn't try to second-guess user actions by default (assuming when they do/don't want perspective mode).
- Its really annoying when it does _NOT_ do what you want, and we got bug reports from users who wonder why their view ortho/perspective is changing - see T39183 T40173
- Its difficult to support under all circumstances, (switching between camera/axis views, axis-snapping by holding Alt while rotating the view for example) - see T40148
I really think we should not enable this by default.
(See main ticket about changing defaults - T37518)