I think the primary issue is that it is a game and what's more, a game which allows players to creatively interact rather like The Sims. If you want the 'authentic Tolkien' you need go no further than a good old book, a game is never going to give you that experience, not least as it will impose on you one 'vision' of the world you are reading about and not allow you to create it for yourself.
However, what is to stop the reader from imagining all kinds of scenarios involving the characters? In fact they do, you only have to look at slash to see that people will and do put say Legolas in a clinch with Aragorn
Those scenarios spring from readers' minds - yet you get few imagined scenarios involving something else 'not mentioned' - flying Elves. Why should readers of books be allowed to have scenarios they like in their own imaginations yet gamers should not?
Maybe the difference is that other gamers would not like to share the virtual Middle-earth with the imaginings of these fans? Do we then have to deal with the prospect of a schism and two parallel Middle-earths?