umm, we can when we sign up. one name is enough. if people changed their names all the time, there would be a pretty big hassle with attributing accurate knowledge and the right reputations. plus it would be pretty easy for a moron to impersonate a great member and royally screw things up. this has been discussed before, and i haven't even listed the real reasons why it won't happen, but it won't
Choosing a login when we sign up isn't changing the login name now is it. Changing a login name would still render you with one name, yes one name is enough. I don't think it would be a big hassle, the account would just have to be identified by something else other than the name then all attributes would stay the same regardless of the login name change, just like when you change any other information in your profile. I don't see how, if a name is gone it's gone. If someone wants to impersonate someone else all they can do is choose a name very similar to the user they wish to impersonate and hope that others don't notice the difference (I think that's far fetched considering the users status is always very visible). Besides, they can do that now anyway. I think it would cause varying degrees of hassle for administration depending on how it's done. Just a suggestion. By the way, you didn't list the real reasons why it won't happen, why? Why list fake ones?
It isn't going to happen. You decide on a name when you join up to aD; don't like it? Well, tough! That's not for you to decide. The mods would have a hard(er) time keeping up with all the little brats running around the site if they were constantly changing their names. Also, the servers would probably skip a beat with all these changes being made. They have enough to handle before we have thousands of people changing their names daily (and that *would* happen)... Not practical. What if you wanted to change back to your old name afterwards? Probably had better things to do. I've told you the two main reasons that a) came up last time this was discussed and/or b) come up whenever things like this are suggested.