Of all of the possible issues with WoW's offline auctions, the added cost is the one that bothers me the least.
Overall, this does not sound like a feature that is going to pay for itself by driving additional subscriptions. (There might be a few econ-minded players who might pay just to play the AH game, I'm just guessing that we're talking about hundreds rather than millions of players.) If, for the sake of argument, we accept that this feature is an improvement to the game (the far bigger issue in this particular case), an additional fee is the only way to make it happen.
By contrast, we have the latest from Star Trek Online, which, on launch day, turns out to be charging for access to races. Klingons are fully implemented as their own faction, but unlocking Klingons who have defected to the Federation will cost players $1.50. Unlocking the Ferengi, who were apparently implemented in beta but not included with either faction, will cost $0.50.
Both types of characters were regulars on the TV shows, so there was clearly going to be some demand to play these races. Rolling up a new alt can actually keep a player occupied for long enough to bring in more subscription dollars. Meanwhile, Cryptic seems to have designed the game system specifically to make the addition of new races relatively easy. This should not have been a feature that needed to end up in the cash shop with a separate price tag in order to make implementing it viable, unless it ended up as a headline feature of a larger paid expansion.
In the end, players have a choice. Those of us who don't feel like playing those characters (or aren't willing to pay even a dollar to do so), don't have to pay. People who distrust the business model sufficiently can choose to skip STO outright. (Between the pre-order races and the new paid zone in Champions Online, players who fear the nickel and dime effect have plenty of reason to stay far far away.)
The catch, of course, is that the vote to quit the game is more of an all-or-nothing decision for both sides. Relatively few players are going to quit rather than try a new alt because they're morally opposed to the $0.50 to unlock the Ferengi. If, on the other hand, the player has used up all of their included character slots, AND would have to pay for additional races in any case, the total bill might add up to a large enough number to make players reconsider. If Cryptic is simply hoping that they already took that player for all they were worth by locking them into a long-term pre-release subscription, they might be in for a very harsh landing in the word of mouth department.