This offer makes sense. You have to wait 7 business days before making a DBT withdrawl, so there is more than meets the eye with the 1x rollover. In addition, DBT transfers have a $500 cap (you can get this raised, but not too much higher) so you are talking about $100 max in bonuses given away per customer.
I am sure the reason they give such great DBT bonuses (just like Wagerstreet and SIA do with their e-checks) is that you cut out 3rd party charges from places like Western Union and Neteller, plus you have to wait at least 7 business days before making a withdrawl. Combine that with the fact that you are giving a book your checking account info and a lot of paranoid sharp bettors will get scared away. I would be very surprised if a promotion like this really costs BoDog that much money, especially given how much their square clientele will surely want to wager on the Super Bowl and its related props.