You answered your own question/critique/whatever it was with that last question.
40k is immensely more popular than LotR. The money goes towards the demand, not the other way around. GW should support 40k regularly, as it's the most played miniatures game by several miles. There are tons of things yet to come out, especially for an army that has been around as long as Tyranids, yet they continue to push it back in favor of a dead "bubble" system? That's just bad business.
Also, if it were a better system to play with, more people would play it. As such, less than 10% of FLGS owners are able to justify the product on their shelves for more than 6 months at a time. It's losing money. There will be a bubble with the release of the two Hobbit films, but then it will die once more.
Tyranids players were basically promised a birthday present in the form of some models and potentially some rules updates, but instead, we get a White Dwarf full of the least relevant game in table top history.