Darling, a lot of it has to do with how the system works.
First off, the inability to download ROMs? Correct me if I'm wrong, hackers, but it's in place to protect you and PC. Think of it like this. Every time you download something, that puts stress on a server -- the thing that keeps a site up. The more stress, the more likely a site is going to go down. Limiting downloads to only members cuts out traffic because not everyone can go and download a hack or whatnot, so there's less stress on PC. (And there's probably something about how it prevents ROM theft as well, but honestly, I don't go in that section enough to know off-hand.)
Second, e-mail activation is a standard procedure. Most bulletin board systems will have you do that somewhere along the lines, so that's more of a general inconvenience when it comes to vBulletin boards instead of actually PC's fault. This is because there's this thing called a "bot," which creates accounts on forums like these to post spam, inappropriate links, things like that. E-mail validation is one way of preventing that because, obviously, one way to figure out whether or not you're an actual person is by having you go and get a real e-mail address and take a few extra steps to prove that you're not a bot.
Third, the fifteen posts thing? Same thing, although that's actually a setting PC chose to have. Sometimes, some bots get through, so to prevent them from posting links to things people really don't want to see, PC has a system in place to keep people from posting links at all until they've established themselves as proper members of forum society. In other words, if you stick around and make fifteen posts that don't get you kicked off the forums, chances are, you're human.
Fourth, hitting the back button before submitting information tends to have a risk of causing you to lose your work, no matter where you type it. This goes especially for anything that doesn't have an automatic save feature (which PC also lacks) because, well, there's nothing saving your work. Your best bet is to copy and paste your post into a word processor document (Word, Google Docs, OpenOffice, whatever) or something else that can save text to be on the safe side, especially if you're writing long posts. (Given the fact that PC has its occasional downtimes now and then, it's always a safe thing to do when you're writing a lot in case you end up with a database error right after you hit submit. Oh, the many times this has happened to me.)
Fifth, the part about a mod having to come and approve your thread was written in bold letters at the bottom of the forum description for ROM Hacking. Because Beginner's Lounge is a subforum of ROM Hacking and because the latter's description says that threads submitted to it and its subforums need to be approved by a moderator, it's probably a good idea to keep an eye on the moderators of that particular subforum to see whether or not your thread would be approved.
Sixth, one important note to know about forum staff if you want to survive in a forum-based culture: they are not your robot servants. Sorry to put it bluntly, but it's true.
Put it this way. The only people you should be concerned about when it comes to approving your thread are the people directly responsible for that particular forum. Those are the names in blue listed at the bottom of the forum. These are the mods, and their main job is to maintain and assist members posting within the forums they're assigned. Above them are the higher staff, whose jobs vary in degrees but aren't solely responsible for any particular forum.
Admins, for example, have their hands full overseeing the general activities of the board -- making sure it runs smoothly, implementing new features, organizing staff/events/whatnot, and responding to serious problems. They leave the job of maintaining individual forums themselves to the mods, and trust me, speaking from experience, it's a very bad idea to have admins take over mod duties. First off, it distracts an admin from performing their actual, more important duties (namely, supporting the board as a whole), and second off, it tends to lead to confusion because the mods begin wondering whether or not they should take action or if an admin is already handling it. (Or, at least, that's what happened with one of the forums I used to run. It wasn't pretty.) Edit: Also, what Sydian has to say is true and probably applies more to this board than my anecdote on how it sometimes messes up the coordination of the staff.
Additionally, also remember that all members of a staff are human beings. They need to log off once in awhile to take care of themselves and the things going on in their lives because forums are meant to be a hobby, not a job that they're required to do. And even then, when they log back in, they'll probably have other things to take care of. For example, Emulation as a whole is a large and active forum. The mods there will probably have reported posts to handle and other threads to look over and approved besides yours. They really do need those twenty-four hours to take care of their real lives, get on, and go through some routine work before getting to you, so the best thing to do is step back, take a deep breath, and chill out. If your thread hasn't appeared after all that time, approach one of the Emulation mods calmly (because remember, they're human, so they probably won't like facing someone who's less than civil about things) and ask. They'll be able to explain things to you clearly and calmly so you can figure out where to go from there.
Point is, it's actually not any more complicated than any other forum, really. A lot of the rules and restrictions PC has in place are there for a reason or are generally standard for any forum. (Heck, I'm not even a hacker, and I get why they do half the things they do there.) The best thing to do, if you want to get by and get the help you need, is just to wait.
Well, that and ask questions without flipping out about it. *sips a bit of tea*