why?

I just realized that Bob's Burgers is kinda a weird choice to get a theatrical film. Like it's popular and liked, but not THAT popular. You'll hear people mention The Simpsons, Family Guy, South Park 100x times individually before even one person mentions Bob's Burgers. I've never met a diehard Bob's Burgers fan, only people that go "yeah, I like that show". I didn't even realize the show had been on for a decade.

Bobs Burgers is better than family guy.

I agreed. Family guy & American dad need their own movie.

Family Guy did have a movie. Stewie Griffin: The Untold Story. Pretty sure it was released straight to DVD but it was a movie. I'm sure if Seth MacFarlane wanted to make an actual big budget one they would let him.