They are making a very ill-informed business decision if they think that the future of internet business involved limiting a consumer's choice, rather than permitting screenscrapers to expand choice.
Consumers typically hate being directed as to what to do - which is why the iPhone is so successful as a product compared to the rather more limited alternatives.
While I am sure that someone within the business truly believes that the increased revenue from forcing the website to be used and raising ancillary revenue exceeds the lost revenue from prohibiting these websites, I do believe they have miscalculated consumers' motivations for using agents as opposed to direct bookings.
You cannot force consumers to be luddites and use only your distribution channel, when greater choice exists elsewhere.
(for those who know what I am talking about - remember Porter wrote about pre-internet distribution channels in 5-forces...)