Why do you think that? Much of the books are scene descriptions, and it's got a lot of action in it. I think it'd translate quite well to TV. Potentially better than Game of Thrones, which is like 90% politics and intrigue.
I can think of a lot of factors. Take the setting: it's pretty easy to approach Game of Thrones as a generic medieval setting, with knights and castles. It's pretty relatable so it's not until you delve more deeply that you see more nuance. The Wheel of Time is largely based on Early Modern Europe, and that's a more unfamiliar concept to communicate. To make matters worse, the stark differences between the societies in the Wheel of Time and our world play a big part in the story, and they're not going to be easy to explain on screen. Just trying to figure how to show off White Tower politics is going to be a big headache.
Next we have the storyline. It's huge, and complicated, and filled to brim with things like the technical bits of the magic system. It's sort of cool in book form, but I don't think that it translates very well.
And there are the characters. There are way more key figures in the Wheel of Time than there are in A Song of Ice and Fire so it's going to be more of a chore to juggle them. It's not too bad in the first couple of books, but starts getting pretty bad by book 3. I also feel that the characters themselves are going to be harder to pull off - the main characters especially seem really modern for the rest of the setting.
Don't get me wrong, I've read the books ages ago, and there are a couple of scenes that I'd love to see depicted. However, I have a hard time imagining them pulling it off successfully.
WoT might play better with modern audiences than GoT. WoT is like a fantasy Star Wars were all the Jedi are women (with a deep story reason why). It definitely gets darker than Star Wars but it is more high fantasy than GoT and all of its rapey shit.
One difference is that the rules for Jedi are fast and loose and a viewer doesn't have to pay that much attention to it. The rules for channeling are complex, dense, and they play an extremely important role in the story.