That's not true. Sci-Fi fantasy shows get noticed for two reasons, writing and effects.
TVD's writing has missed the mark on older audiences. It is primarily a character driven show and not a story driven show. Its main character has as much hate as love within its on fanon. TVD decided not to go too supernatural. It saves money for special effects but never gets in the running for the award category.
AS for Sci-Fi, fantasy shows getting nominated, a few big ones:
Game of Thrones 59 nomnations. 10 wins so far
American Horror Story has been nominated for 17. 4 wins
Walking Dead 6 nominations. 2 wins
Lost 24 nominations. 4 wins
Battlestar Galactica 8 nominations. 3 Wins
Buffy the Vampire Slayer 10 nominations. 2 Wins
Angel 1 nomination.
The X-files 21 nominations. 3 Wins
Quantum Leap 8 nominations. 4 wins
Touched by Angel 12 nominations.
There has always, always been one sci-fi fantasy show to win something.