Thanks guys for all the inputs!

Unfortunately, this is a niche promotion geared towards people spending their own money to stay at Hilton properties.

15% off a $150.00 per night room is $22.50. ($50.00 for 2 nights) If your plans are firm, this is a great way to earn double stay credits on a non-refundable rate without having to switch hotels. Yes, it’s worth losing the extra points because you can take that $50.00 that you saved and purchase 4,000 points on the HHonors site, which is probably more than you would earn on a stay at this rate.

Business travelers, in most case, can’t do this. Therefore it isn’t nearly as attractive. I’d much rather pay a little extra on my company’s dime, earn points for both nights, earn the same amount of stays and have the ability to cancel my reservation if something came up.

Price discrimination at its finest.

It is basically 'pay in advance' and you get to save some money.
Not sure how that's price discrimination. if you have plans that will not change and wish to take the chance your plans won't change, you can book it and save money.

Otherwise, wait till later or book the BAR or your corporate rate (if applicable) and you get the benefits of getting to cancel if needed.

It is absolutely price discrimination, of the third degree. It offers the same service at a different price to different segments of the market, and in this case is offering a favourable price to customers who do not require flexibility and want to stay on weekends.

Note that price discrimination has a particular economic definition. Please google it if you are not familiar.

If you have a look at some hotels, they are offering the rate everyday. I have booked across europe and the rates are offered anyday.

This offer was supposed to finish 31 January 2013. Just found that it's still available in Asia. Available at hotels in Hong Kong, Singapore and Thailand. My mistake, just noticed that for Asia hotels, the offer is due to finish 14 Feb 2013, even though the Hhonors website states that the offer has finished.

That's right, it's stated in the fine print of the offer page. Here's the link if you're doing any bookings in Asia.