ALeveling now is a godsend. It doesn't take more than a week at 2-4 hours a day...
Don't even try. Don't. Even. Try.
I wanted a 90 monk as soon as possible in MoP, right? So I used RaF grant-a-levels from 12-80. I finished the Panda starter zone in a day, then flat out blasted to 90 as quickly as I could. No professions. Didn't log into my bank alt. Had as many heirlooms as my level warranted.
36 hours (and 2 minutes and 31 seconds) from 80 to 90.
2-4 hours a day, let's say 3. A week. That's 21 hours.
It's 36 hours from 80 to 90 (plus Panda starter zone). You're saying it takes 21 from 1-90.
It takes 60+ hours to get to 90. Probably 80. That's just powerlevelling, too. Nothing else. No professions, no AH-ing, no gathering, nothing. My Warrior has 3 days, 21 hours played- and 21 hours at current level. 3 days to 90, from level 1. That's 72 hours.
If you want to hit 90 in a week, you need to play for over 10 hours a day. TEN. HOURS. A DAY.
Let's say you can play for 2-3 hours a day. That's a month or so. An entire month, spent only levelling one character as quickly as possible.
That is obscenely long.
If it was a month of enjoyable content, a month of actual questing, maybe.
But no. It's a month of "GET ME 10 MORE BEAR BUTTS" "GET ME 3 LEAVES" "KILL THIS ONE SPECIFIC GUY" "GO HERE". Nothing else. Nothing interesting. Nothing different, other than the scenery. Just repeatedly the same ideas with different enemies. That's it.
Blizz really needs to overhaul the entire concept of questing. I know it's blasphemy to bring it up here- but Runescape got questing RIGHT. Take a look at this:
That is one single quest. One. Single. Quest. Blizz needs to make each zone one ultra-massive quest, like that, which is actually interesting and engaging, and it instantly bumps you up one or two level(s) when you finish it. Not YET ANOTHER "KILL 12 MOGU PLZ I'M INCOMPETENT AT COMBAT DESPITE BEING LEVEL 90 ELITE AND EXACTLY 12 WILL TOTALLY MAKE A DIFFERENCE" quest.