I also like to read stand-alone novels or shorter series. My point is that if the plot, the characters & the world interest me, I'm not scared of reading such a monster series, even if one has to deal with some slower parts, has to keep lots of plot-lines, characters, etc., in mind, and be rather patient for the resolutions.

On the other hand, I would argue that simply the length of a series like WoT is wearing Roberts down, especially if he normally reads shorter works with less details, perhaps has a shorter attention span and might be easily bored (as you said, he e.g. probably didn't even realize what the damn point of the plot in TFoH is). This is supported by Roberts' "reviews", which in my view become more and more sketchy, mediocre and contain mistakes, probably because he is only able to read the books very superficially. If he would devote just a bit more time to really read the books, he might eventually see some worth in WoT (and e.g. maybe even get why the 5th book is called "The Fires of Heaven"..). Of course, Roberts actually doesn't want to give WoT this chance, so his "reviews" might be mildly amusing in some parts, but overall they are pointless.