Yes, but not with Gyrados. He's as good as he will ever be, so evolve if you want to. I caught a 100% Magikarp during the previous Kanto event and the only reason I haven't evolved mine is I have over 40 Kyogres, so it seems pointless to evolve another Gyrados.
But I agree with you. I'm sitting on two 98% female Ralts because I'm hoping Gardevoir will get a fairy fast move and I have a feeling if she gets one it will be a Community Day exclusive and I probably won't evolve a Garchomp until Gible Community Day because Niantic will probably give Garchomp trash moves when gen 4 comes out.
I love that Community Day moves made Venusaur and Charizard relevant and gave Dragonite another strong Dragon move even if not as good as Outrage, but giving great Pokemon trash moves while saving the good ones for Community Day feels like a lousy way to treat players.