Elves may be fictional creatures but the setting forgotten Realms describes pretty well how elves should look like. Disregard a whole setting because "Oh hey its fictional everything goes" actually don't give the setting proper respect.
Well, I don't think this setting deserves much respect. The D&D creators had no problems "borrowing" from Tolkien (and other authors) in the first place, and had no problems changing this lore once they got faced with a lawsuit.
Then why you are even here?.... If you dislike this setting so much why playing a game in this setting?.. If i dislike soup i don't eat soup. Also keep in mind there are people that may love the setting.
I like the BG game series just fine. This doesn't mean I'll believe the soup is cooked from an original recipe. D&D creators had a loose approach to the works of others, and only got careful about it because they got threatened with legal action, so I'd say they weren't giving other creators proper respect either.