Drysc then shows up in the thread and affirms that Blizzard isn't worried about lower levels being in Outland, and then says the reason for this was to keep lowbies from rushing the new content during the Burning Crusade launch (as happened on many servers during the AQ gate opening. A player then asks the kicker: since the launch is long over, and any lowbies are welcome to explore their curiosity at any time (for the price of a simple summon), when will the level restriction on the Dark Portal be lifted? Drysc, caught speechless (at least, in my imagination he is), says simply, "I'm not sure."
So it's conceivable that Blizzard could, at some point, lift the level 58 restriction on going to Outland. The only problem is: who cares? While there are a few level 58-60 mobs in Hellfire Peninsula, anyone lower than that is going to get mauled everywhere else. I suppose that with an escort, lowbies might want to go out there to work on their profession skills, but for most skills, 300-375 require at least level 50. I'm not sure if First Aid has the same restrictions-- I guess that players might be able to go to Outland, get the First Aid books, and then go into sub-58 battlegrounds with better bandages than others at that level. And setting your hearth to Shat early doesn't hurt-- it gives you access to every big city in the game. Are there any reasons at all lowbies might want to get into Outland early?