"Timing is everything". This line seemed to be in the spotlight right after the market "peaked" from my observation. Lord of the Rings theme is a very interesting one, and for no particularly good reason I'll toss in my 2 cents:
I think a lot of collectors/investors assumed this would be a slam dunk, as it seemed to target the market we covet - Geeky types with extra money.
I also think this theme retired RIGHT AROUND the time the "secret" about LEGO investing started getting out, which meant increasing competition and lower profits around the board.
The line also gets a bit of a bad rep, since people expected to do SO WELL, anything less is considered a disappointment. But like many sets/themes, if you bought at 50% discount, every single set from the LOTR line (except for 79008 Pirate Ship Ambush) will at least double your money. And even 79008 should make someone a decent profit if purchased at 50%. For some, it took 2-3 years instead of 1-2, but that is the new normal. I don't consider Helm's Deep or this line at all to be a loser. Not every set from every line is a winner.
Similarly, The Hobbit line is full of mostly winners. Goblin King Battle and Mirkwood Spiders are the worst performers but will still make you money. Almost every other set will have doubled your buy in at 50% after 2-3 years. Not too shabby.
This line really came and went at a turning point in LEGO investing, and in general, the profits have been lower and the time to achieve them has been higher since. The Tower of Orthanc also as the crown jewel, came out at a time where exclusives were no longer sure things and the profits weren't nearly worth the buy in and wait time.
I put Monster Fighters and Haunted House in the same category, because these were great sets that have performed comparatively mediocre - when looking at the lines that retired the couples years before.
I don't regret a single dollar I invested in either of these two themes, and I think the sets from both are fantastic quality and builds. They are kind of the "Shark Jumpers" in the world of LEGO investing however, and will be associated with that downturn. The numbers/ease just won't ever be where they once were, and that sticks in a lot of folks craws.