It's hard to say how much of a desperation move this is. There are a lot of really good reasons to throw a discount like this out there.
1) They could be thinking that there are a lot of free to play accounts that would go all access by throwing out this deal. In this case, it's money they would not have received otherwise.
2) Would some people who otherwise would pay $15 per month go the cheaper route and get this deal? Sure, but if time value of money teaches us anything, it's money now > money in the future.
3) It could be a move to grab a few more $$ before the WoW expansion comes out and takes away some paying customers for a period of time.
4) They could be approaching the end of a fiscal period and want to inflate the financials a little. A lot of companies have specials to boost revenue near the end of their fiscal year to make the financials look better.
5) If it were a desperate money grab, you normally would extend this to the beginning of the month when fixed income and some other workers in different sectors get paid. The fact that they are doing this at the end of the month suggests otherwise.
6) Finally, and this might be a bit of a reach, but they could be trying to bring down krono prices to a more manageable level by reducing demand.
Those are just a few of the reasons off the top of my head for all the chicken littles out there.
