I never managed to finish any of the LotR books. Everything I know about is from:
a) Lots of excerpts read in bookshops over the years, whenever I thought I might buy the books
b) Lots of secondary sources, both critical and reader response (the Morgan article, IMO, is the latter)
c) Discussions with people who have read it, some who liked it and some who didn't, and some who know the Silmarillion by heart.
d) The films (both the animated earlier one, and the recent trilogy)
Now, the interesting thing is this: I did read and enjoy The Hobbit. So why can't I get into the LotR?
Personally, I think Tolkien is giving me trouble finding a reading mode. Sometime's it's a fairy tale, sometimes it's an epic, and sometimes it's social realist novel, and it never really comes together for me. This may actually also be Morgan's problem: there's stuff in there that interests him, but it's buried in more stuff that doesn't interest him. If it were a fully fledged epic, singing the praise of our heroes (like, say, Beowolf), or if it was a fairy tale string of adventures (like The Hobbit, which I actually enjoyed) you could deal with it on that level. But that's not what it was. It's way more complex.
For some it comes together, and for others it doesn't. You're right (in your blog entry) that we shouldn't criticise Tolkien for what we think he should have written. But it's somewhat harder if he taunts us with intersting snippets. It's almost like: look, this is what I could have written, but I didn't really want to. Under certain readings, it's almost as if Tolkien criticises himself.
Again, this is just a superficial impression, based on my inability to get into the text, and on the fact that it's not Tolkien that puts me off (I like The Hobbit).