Automan_Empire - 2:01 am on Oct 18, 2006 (gmt 0)
As long as the username/email addy are PRIVATE, as in viewable to the individual customer only, it is useful and convenient! I truly hate having usernames and passwords galore all over the internet.
On the other hand, if you will ever add features like a user forum, or anything else where others' usernames will be visible to other customers, you run into problems of the names being harvested by spammers. Even the PERCEPTION that this might happen somehow is a big potential turnoff to would-be customers.