The problem is that LOTR has no cartoon/show to support it, if they had a Hobbit or LOTR show (not live-action) children would love it and possibly buy sets. As well as that, LEGO Star Wars have many "impulse" sets that include lots of playability as well as battle packs for even more fun with their new blasters.
And you have to think about it, if a kid is neutral in terms of Fantasy/Sci-Fi orientation, would he/she rather buy four battle packs, including sixteen troops for "huge" battle scenes and maybe build their own scenery or even use furniture, or would they buy one set (MEA) that includes a few elves a warg and a couple orcs with a fort that will probably get dismantled anyways. Of course they would buy more quantity and even then, the quality is on par especially if you are talking about the 2015 sets coming soon.