I'm mildly in favor of the 4 weeks. I don't think it is that big a deal either way. But I do strongly disagree with this:

Part of what makes Steem a community is that people can't just up and leave

What makes a strong community is that people can leave but choose not to. They renew their ties every day when they decide to stay. A "community" where people can't leave is a cult or a prison.