I disagree on some of those points.
1. How would this make the forum lag? Sigs are changed all the time. And so are post counts and locations.
2. Only allow name changes once a month, and have a Formerly Known As \'insert name\' tag. Like the location tag. Problem solved.
3. Why would this change? You are buddy/ignoring the user, not their name. Your lists would simply change with the names.
4. There
is good reason to change your name. Role-playing. If your character changes or evolves, then you may wish to change your name to evolve with it. Take me for example. My username was chosen purely for RP purposes; it isn\'t my name, it is where my character started. When the time is right, it will be changed. As for creating a new account, this contradicts your #3 statement.
Also, not-liking-your-name-and-creating-a-new-account would and does create many dead accounts and actually misrepresents the number of PS members. Do you think that there are 10471 PSers and no duplicates.
It seems that I disagree with all of your points (besides the banning, that would be silly)

.
I, personally, would like to keep my current account when my true IC name is given.
However, none of this is likely to happen.