Why Would Delta Reintroduce Its Online Purchase Bonus?

(MoneyWatch)  Delta put out an odd little piece of news on Tuesday when it was announced that it was bringing back a 500 mile bonus for everyone who books on delta.com (or Worldperks members who book on nwa.com). Every airline had slowly gotten rid of the bonus because they found they didn't need to offer the incentive to get people online anymore. So why is it back?

There are a couple of theories on this one. One is that the Delta/Northwest merger might create some sort of confusion and they want to just offer a little bump to keep people coming to the websites. The other, as picked up by Ben Mutzabaugh over at USA Today, is that this is meant to fight the online travel agents who have now eliminated booking fees for a short time.

I tend to think the latter is right. It was actually Tom Botts and Chris McGinnis that both brought this up. Online travel agents have killed booking fees through 5/31, and that is also when Delta's promo ends. So it's likely that either Delta is seeing the online travel agents take back some share or they want to make sure that it doesn't happen preemptively.

Either way, I don't think this is going to really move share very much. Those who really care about the 500 mile bonus are probably already booking on their site. But it's a cheap promotion, so if it does help keep online travel agents at bay, then it's not a terrible thing to try.