My own experience with LotR is more complex. I got into D&D in the mid-90s when I was in the Navy and wanted to read LotR because I was given to believe that it's contents reflected the background info in AD&D books. I started with The Hobbit, and I enjoyed it. When I got to Fellowship, however, I found that I didn't like it. I stopped a little more than half way through Fellowship. Mostly, I didn't like the pacing. But I also felt like I was reading a scholarly work where I didn't know all the terms of art and was missing half the information I needed to enjoy it.
My experience with LotR kept me from reading more fantasy. I figured that since most fantasy was inspired by LotR, then I probably wouldn't like it. (I did read Liber's stories though) Recently, I started reading Howard's Conan stories (which, I recently learned, pre-date the Hobbit) and really enjoyed them. I remember working at a game store and a customer saying that Tolkin was the greatest fantasy writer ever I said I didn't think so. He asked me to name someone better. Since I didn't read a lot of fantasy though, I said I didn't have a better one in mind. But that's been pretty much my attitude, I can't really criticize someone's writing if I don't enjoy the genere they're writing in. Now that I've read more, I feel like I can revisit the books.
I actually haven't encountered a lot of strong criticism of LotR. I've seen gamers who acknowledge there are aspects of it they don't like, but few people actively
dislike it. Mind you, I've seen non-gamers who don't like Tolkin at all.
My understanding is more that our thoughts and preferences on pacing have changed since Tolkien's day.
It's been awhile since I've last checked the books out, but I think you're wrong. For example, The Thirty-Nine Steps by John Buchan is very fast paced. It was published in the UK in 1915, several decades before LotR.
Of course, The Thirty-Nine Steps isn't fantasy, but there's a difference between LotR and other fantasy stories is that a lot fantasy was published in pulp magazines first. This means that the dominate form was short stories or serialized novels or novellas. A novel meant to be serialized in a magazine is going to have different pacing than a novel meant to be published at once, but spread out in three novel-sized books. So, while I can claim out that Howard's Conan stories are better paced than LotR, we run into the problem that Howard was writing for a different outlet.
Certainly, most of the stuff I've read that was published before LotR or around the same time is paced, IMO, better. Certainly pulp novels like A Princess of Mars are paced
very differently from LotR