Backwards compatibility. You remember all those folks complaining about Python 2 vs 3? Turns out even renaming Thread.isalive to is_alive caused a ruckus. Imagine how much yelling you'd hear if you changed float to Float.

I've come to like the self variable name convention. It takes so little effort to type and makes the behavior more clear. Well, some aspects of it, I suppose. I make a fair amount of use of unbound methods.