Unable to change username (User ID), but no reason given

[xobzoo]

When I registered, I was neither prompted for nor obviously assigned a "User ID" — which should've made me suspicious.  Unfortunately, I didn't even think about that because it had me enter my email.  (I wasn't thinking about how seller's email addresses are not listed, just their usernames.)

After registering, I went to inspect my information, to see what I could see.

I saw a stupid username that was generated for me, but which was ugly.

Much digging around later, I finally got to a place that claimed it would let me change my username.  Except it didn't work.  Despite following the username policy exactly. ( http://pages.ebay.com/help/policies/identity-user-ids.html )

In frustration (and curiosity if it was just straight-up broken), I changed a letter to a number, and it suddenly worked.  Which defeated my assumption that 6-character usernames were restricted, and the document just hadn't been updated yet.

To be clear, my intended username

• is not obscene or profane
• does not contain anything resembling the word "ebay", nor an email address or URL
• has no symbols or numbers in it (it's straight alphabetic)
• does not contain the letter 'e' so certainly is not "The letter e followed by numbers."
• is not another user's name (and I'm 99.9% certain it does not even resemble anybody else's name, though I can't prove it without having a complete list of all users)
• does not resemble and is not confuseable with any 3rd-party trademark or brand

So now it appears that I'm stuck with a name that isn't really mine for 30+ days while the cool-down occurs.  And no real hope that I'll be able to fix it after those 30 days anyway, since I wasn't able to do it the first time.

Is there some hidden rule I wasn't told about that prevents certain proposed usernames?

Also, why isn't picking a username part of the registration process?  And why aren't we warned what it's going to be?  I was shocked (and appalled) at mine when I saw it.  I want my username to reflect me.