You're forgetting that WoW has been around for what, ten years? (Never played it, no interest in playing it, forgive me for pulling the number out at a guess, but it should get the point across), whereas ARR is still under a year old, not counting beta time. Back at launch, it was near impossible to play because the servers were so full, it even existing players couldn't login. Servers are capped on how many characters may be logged in at once, and if they keep the servers open for character creation at all times, it'll just go back to that -or the days when extended periods of inactivity were an auto-logout.

Don't get me wrong, this annoys me as much as anyone, but I doubt it's being changed just yet. Give it some time; restrictions will ease up later on. Just get them to register during the window when character creation IS open, it's what I've had to do when I've wanted to make alts, and the same for the rest of my FC.