All of your concerns are valid and noted, but our take on it is that we want the forums to be free and easy for everyone to use.
Think about it this way: whenever I go to other forums, if there is a waiting period or a post requirement to do something I want to do, I skip using that forum and move on to somewhere else. We don't want people to do that here, as we want everyone to feel welcome. The unfortunate consequence of that is that sometimes it's easier for spammers to do their work, but it's also actually pretty easy for our moderators to clean up after them, so we choose to go that route. We're sorry that it means that sometimes there are spam threads around, but is it really that big a deal if now and then there's a thread that you just don't read?