Please remove most of/all obsolete code. There's now extreme amounts of code left overs since the early days cluttering down intellisense for no reason. Some major pains are the public static methods in Quaternion, GameObject and the default components in all Objects.
I'm a teacher trying to teach people to use Unity, and telling people they have to make a new variable and reference it to the assigned Rigidbody instead of just using ".rigidbody" is a major confusing for a lot of people. Not to mention that you'll have to hide the member using "new" if you want to use that particular name.
I feel like this is long overdue now. With the introduction of a new Versioning system (since 201x.x) it's a perfect opportunity to break some backwards compatibility for once. If people still want to work on their legacy code they'll just have to upgrade or suck it up. The clutter is starting to get real.