The World of Men
First of all, we're in the boringest part of Middle-Earth, and gonna stay there from here forward. Rohan and Gondor are where I lose interest in The Lord of the Rings (the books), and so it's hardly surprising that it's where I should lose interest in a game that follows the storyline. When I'm in Middle-Earth, I want to hear about elves first, hobbits second, dwarves third, and anything else (including humans) a distant fourth. Humans are there because they have to be, but they are boring, boring, boring, boring. LotRO has been to Rivendell and been to Lothlorien. The only place I want to go that it hasn't been yet is Northern Mirkwood... and having been to Southern Mirkwood, that's probably close enough to call it a day.
If there was a Silmarillion Online, I'd jump ship in a heartbeat. It'd be depressing, sure, but at least it would be interestingly depressing.
MOAR Levels, MOAR Mechanics
Every time they release a new expansion, they scramble the game mechanics, especially for my favorite class, the Warden. I learned the Warden when it was new, then I re-learned it when they shuffled it the first time, then I started to re-learn it when they shuffled it the second time and made all the stances do weird things, and now they've added mounted combat to the mix and... to hell with it. I don't care enough to re-learn the class a fourth time. -.- That leaves me with the Champion, and there's really no point to me playing a champ because in any group I'd be likely to join, jamesbarrett's raid-gear-and-all-traits-ground-to-50 champ would make me superfluous anyway. It'd be all right for going through solo content, but since as mentioned that's all in the World of Men, that's hardly a compelling argument.
I did make a Runekeeper (my Badass Lightning Girl) and got her to a fairly high level, but I was never that great with the class, and it's another one that's constantly getting scrambled like the warden. Meh.
Time, Destroyer of All Things
The final element is of course my very limited leisure time. Even when I'm not trying to work on a comic, all sorts of junk keeps happening that I have to deal with, and so I have to be very choosy about what I do with my time. Right now, #TwitterPonies and Borderlands are way more fun than LotRO, so if I only have an hour in which to goof off, why should I pick the runner-up?
It is conceivable that I might become interested in LotRO again sometime; I go through cycles of interest all the time. That's why I've continued to sign on and pay my rent. But I don't know if/when that will happen. So until then, folks will just have to march against Mordor without me.
PS: I totally typed "The Lord of the Rinds" as a typo in the draft of this post. Now I want to do something with that idea.