It is very unlikely that we will be deleting anyone.
There is no technical benefit in doing so, and wont make anything load faster.
The user data itself is probably only a few hundred KB or maybe a couple MB max. Whereas everyones private messages, take up hundreds of MB, or the forum data itself which is also about as big.

I would rather have someone who hasnt been by for a while to be able to still log in. I personally hate it when a site deletes my account for being 'inactive'.

And when you join utadanet, you MUST provide an email. It is needed to ensure you are not a spammer or spambot or incase you forget your password.

And Utada with 7500+ english-speaking fans looks good to me.