Two words: Future-proofing.
Macs are expensive, and many Mac users cannot afford or do not want to buy new Macs frequently. Such Mac users want to buy a Mac and have it work with the latest software and peripherals for as many years as possible. For such users, it makes total sense to want a Mac with Thunderbolt, even though there are isn't a single Thunderbolt peripheral on the market.
I absolutely agree. This is the same reason why I was hoping the USB 3.0 would be on this version. I realize now that is almost certainly not going to happen. I just thought that with so many PC's (including some PC laptops) already offering USB 3.0 that maybe the brand spankin' new iMac might be so equipped.
I was wondering why so many people are so opposed to Apple offering Blu-Ray as a BTO option. I have read where Steve Jobs spoke negatively about Blu-Ray, I wonder if these same people would be all gung-ho for BR if Jobs had spoken positively about it? I realize that he is a very smart man, but he isn't God! I always thought that BR would have been a great thing to have on a Mac for things like backing up your iTunes library. Imagine that, being able to back up your entire iTunes library on two or three BR discs. That would have been really nice. I read somewhere the other day that they either have or are getting ready to have BR discs that have a 100GB capacity. What in the world would have been wrong with that?