I don't understand what is the reason to make users wait. Of course free accounts shouldn't be given to everybody because spammers and hoarders will get them.
Currently Steemit is giving away free steem with new accounts, because an account needs certain amount of Steem Power (which is locked steem). If Steemit sold accounts, they could give a little discount for anybody who wants to buy some extra SP when they create the account, so it's always cheaper than market price.
Honestly I don't know why, but being a software architect there always unseen mountains and valleys to climb before a great product is accomplished. I like the idea selling the accounts.
AFAIK this is more a business decision rather than a software problem.