I think your wrong there: WOT has plenty of those little mysteries and plot twists and character moments that would leave the audience guessing etc. A lot of the humour that gets tedious in the books would very likely be very funny handled by good actors (arms beneath breasts, sniffing and braid pulling gets old as you ead... but on screen it could be really funny if the show doesn't take itself too seriously.. a tone like the last Robin Hood BBC series would work well for WOT).

Outside the readership, a WOT show might just attract more the type of people who loved shows like Lost or even Heroes than the kind HBO hopes to attract beside GRMM's fans. Different demographics, that's all.

You still have a very good point, but I would put it differently: WOT is very episodic and has plenty of subplots that would on the surface make it extremely suitabl to a TV show (and that type of story does well on TV, in other genres). WOT's huge problem is that it's central storyline is way, way to thin to keep an audience interested for the 6-7 seasons needed to complete the series, and if you start streamlining it to do it in 3 seasons, let's say, you end up with a very generic and very formulaic Tolkien rip-off. Readers are more patient.. on average they spend few hours with a new WOT book then move on until the next one comes out. The situation would be extremely different if WOT demanded to be loyal to a weekly show for 6-7 seasons. People found the mid-series terribly slow.. imagine if those books unfolded a few chapters a week only...

The main story is just too thin to sustain a series of that length on screen (many already have this opinion of the books...)