It's a conscious trade-off. One fear is that having comments that are edited after the discussion has taken place will reduce the utility of the future archive. There is also the hope that the current window-of-edit policy encourages people to do a better job the first time while still allowing them to catch silly errors.

I'm pretty sure that if you ask nicely by email that you can find an admin who will remove your email for you. Just wondering --- is there a reason you feel you have to remove it at this point?