Conversely, I think putting races like tieflings, dragonborn, and the like sends the message that D&D isn't just a poor man's Tolkien (and Tolkien-knockoff) simulator. Which I think is the right message to send in a modern system. The boundaries of what is considered generic fantasy have expanded a lot in the last couple of decades, and I don't think you'd find a whole lot of younger fantasy fans, especially, who would consider dragonfolk or half-demons to be anything out of the ordinary. If races like tiefling were ever "cool and dark and gritty", it was a long time ago. At this point, I think distancing D&D from the idea that "generic fantasy" means human, dwarf, elf, halfling is a good thing, because the larger culture has long since done so.