I down shift every time I slow down. Accelerating up to speed is easier and faster. And my gear ratio is higher than what would be practical on a fixie, meaning my top speed is higher.
Still, there is something to say for the simplicity of a fixie
I don't get the hate tbh, I'm nervous to ever ride one myself but you can get going SO FAST, and they're cheap and easy to maintain. I think people used to hate on brakeless ones as a hipster thing tho. I used to ride a single speed and had someone yell at me from their car something stupid because they thought it was fixed lol.