It costs some database space and lookup time. Back when the game was launched I think it made some more sense, but now, I'd suggest that player that actually played for a few months (or even a month) be exempt from the account deletions.
It'd go a little ways towards fostering better relations with the players. It's a little thing after all, but that's what you'll need to really foster the "we're all friends playing together" environment that I keep hearing as the goal.
Really, you'd just need to find the code that handles account deletions then add a way for it to check the account's creation date versus it's last login and not delete anything over 30 days or 3 months or whatever. If you want to cut down on processing time, you could add a new database field that's a simple true/false check on whether the account is eligible for deletion, and have a code that 1) checks for that, does math to see if it needs updating, updates it and 2) only deletes account where that isn't set to whatever keeps accounts from deleting.
