I never said LOTR should be read solely as allegory, I correctly said there were aspects of the novel allegorically connected to WWII and Tokien's Catholicism, even Tolkien admitted as much. Also, a writer doesn't get to determine how his or her text is read, just as a painter doesn't get to determine how a painting is viewed. That's not how artistic phenomenology or criticism works. And again, your description of imagination doesn't make Tolkien's writing greater than Fantasy either. Many writers of Fantasy use creative imagination quite well, and being a learned man doesn't necessarily lead to greater writing. Many learned men have written terrible fiction and many unlearned ones have written excellent fiction.
Also, writing realistic war scenes doesn't necessarily elevate Fantasy. Great literature, and even great Fantasy, requires much more than realistic battles. And well-researched authors often write great battle scenes, as well as great scenes of everything. If people could only write well of their own experience, over 90% of great literature would be discounted. Shakespeare never occupied battle-torn Scotland, and Thomas Pynchon never lived in WWII Europe either, but they wrote fantastic literature about those times and places. So, whether or not you consider Fantasy "misleading,' LOTR is fantasy...whether that genre existed or not at the time.