1 hour would be acceptable.

30 minutes is too short.

I'd prefer if it was removed completely but I understand this is a smart business move for SE. They can cram more players on the servers if there aren't AFKers taking up connections.

SE probably wanted to auto-logout from the beginning but thought there would be backlash. Now they are enjoying the playerbase making the decision for them. Save lots of cash not having to create more servers.