I actually have read Tamsyn Muir. Albeit just the first one.
But yeah, I read very little fantasy/sci-fi these days. Off the top of my head, all I've read of recent-ish genre literature is Harrow the Ninth, A Memory Called Empire and its sequel, A Hundred Thousand Kingdoms and I think part of the sequel, The Priory of the Orange Tree, Babel if you count that (it's really more a rant about real-world colonialism than it is spec fic), The Poppy War, the first book of Tad Williams' MST reboot, perhaps one or two more I forget now.
So my assessment of what is and isn't popular these days is more based on what I see in bookstores, than on what I've actually read.
He may be the biggest name in the field, but is he as big as Jordan, Martin, Erikson, even Goodkind got back in the 90s and 2000s? Compared to other would-be successors of that generation, like Patrick Rothfuss or Scott Lynch, at least he's still going with his series and for all I know it may be pretty good, but what I see of fantasy sections in bookstores is heavily tilted to the YA and 'romantasy' stuff these days.
Yeah, I don't think WoT is on a level with LotR though... and honestly, the length thing, LotR is still a reasonable length for new people to get into and then after that you can decide step by step how far down the lore rabbit hole (hobbit hole?) you want to go. WoT is crazy long by itself.

Never heard of those other two, though the name of Dickinson's series did sound vaguely familiar.