The website and the store both have feedback forums that are fairly on topic and consolidated. The relevant employees at Turbine can look in those forums and see what people think about their products.
The actual game though has rather amorphous discussion and feedback sub forums. This creates lots of really interesting stuff, but not if you are a developer looking for feedback on the particular area of the game you are working on.
I suggest creating feedback forums for each developer with any interest in getting feedback about the areas of the game that they deal with. The devs can use these forums to gather specific information they are looking for at the time or to get a general idea of what stuff they are doing that people love and what stuff people are not too thrilled about as long as eight million suggestions on what would make that thing better.
By providing a centralized location for feedback and customer interaction with specific developers, who see value in this, it will improve the quantity, quality, and speed that the developers can access this data.