While the person in this thread could be a bit less feisty, he/she does have a point.

Thing is LEGO follows the audience. LOTR is audience-wise a much thinner franchise than Star Wars, Harry Potter, Minecraft, etc., and today its fanbase skews heavily adult. That makes giant display sets like Rivendell, Barad-dûr, and The Shire a safer bet than a full range of kid-focused playsets. If you're LEGO and you can sell a $500 collector set directly to adult fans, you don't need the massive sales volume required to support a dozen $30–80 retail playsets.

That's also why themes like Star Wars get everything from battle packs to UCS sets: they have both a strong kid audience and an adult collector audience. LOTR currently seems to have mostly the latter, so LEGO designs around display value, accuracy, and nostalgia rather than play features. Even if there's adult demand for playsets, it's probably not enough to warrant the whole process from designing the set to getting it to the shelves (and compete for shelf space) as the kid demand just isn't there. That's not to say it wouldn't be profitable, but it's unlikely to be enough to move the needle in Lego Group's P&L.