Tubeless road tyres?

Can anyone explain why tubeless tyres are such an advantage for road bicycles?  The push towards tubeless tyres is exemplified by this review of Easton tubeless aero wheels at Velonews. Early in the review, we see this:

Cars, motorcycles, and mountain bikes use tubeless clincher-style tires almost exclusively. Road bikes are one of the few wheeled vehicles that still rely on tubes to hold air. And tubes go flat. A clincher rim with a solid spoke bed (and a few design tweaks to help the tire bead seat against the rim) is capable of running tubeless with minimal changes. A special valve, a tubeless-specific tire, and a little sealant are all that is required. Nipples thread into the inner diameter of the rim. And if anything goes wrong with the tubeless setup, these wheels can be used as standard clinchers as well. The EC90 Aero 55 clincher was designed to run tubeless without the additional headache and pieces involved in converting a standard clincher. More shallow aluminum (read: not aero) road rims wheels are adopting this construction, and the EC90 Aero 55 is the first aero wheel to do so. Tubeless specific tires are thicker than standard tires, so rolling resistance is a factor when deciding to use a tube or tubeless setup for a race, although practically eliminating flats is a very appealing advantage. While tubeless road wheels haven’t yet exploded as they did for mountain bikes, nearly 30 tubeless tires are currently available and the number is growing.

I really wasn't aware that mountain bikes almost exclusively use tubeless tyres - is this an American thing? Apparently the fact that tubes puncture is a reason to go tubeless - but to puncture a tube, the tyre has to be punctured first. And it seems as though the response to puncturing a tubeless tyre is to put a tube in, and that'll presumably be mucky with the sealant that's needed!  Oh and only a few tyres are available, and they tend to have higher rolling resistance. I can't help feeling that tubeless road tyres are a solution in desperate need of a problem! On the other hand, I presume Easton figure there's a market out there for high spec tubeless wheelsets.