The above is, of course, not logically accurate. A large percentage of people accepted it because they didn't mind it. That's way different from it being a useful service.

However, the whole game has changed recently. A couple of years ago, the rare times I saw DCC it was around 3% and most people didn't have fee-free credit cards. If my credit card charges 2.7-3% and the DCC charge is 3%, do I really care? If have to be charged by someone, I might even prefer to give the merchant's bank the 3% instead of my credit card's bank.

Since then, three things have changed:
1) More banks (at least in the USA) are offering credit cards with no foreign exchange fee.
2) More banks (esp. in Australia, though I've read of the USA too) are charging a foreign transaction fee even if the transaction is in their own currency, which makes DCC an addition, not an alternative, to the issuing bank's charge!
3) Most importantly, DCC charges can be 5%, which is way above what any credit card charges and therefore totally unacceptable and uncompetitive in all cases.

It will take time for consumers to realise that what used to be an innocuous choice has become a major rip-off due to those three factors.