I agree.
I have 2 accounts, but 1 account only has 3 80's on it. Unfortunately, my main toon is on this account.
I want to get the achievements for having all classes to level 80 (which my other account does have that achievement), and have most of the offline levels to do this, just can't be bothered to level 9 more toons to level 30 just to pop them to 80.
At least drop the requirement to level 20 to make it less painful, or even lower.