We routinely get e-mails from people who joined a long time ago but forgot their passwords, login names, or changed e-mail addresses. Since we have no way of knowing which of the old, inactive user accounts are truly gone for good, purging any of them would be unfair to those that may some day return. Plus, it's a generally accepted practice on the internet to keep user accounts for as long as a website exists. An extra 30-40k accounts is a tiny amount of data for us to store compared to, say, photo attachments. Bottom line is we have no intention of deleting old inactive accounts.
