Loads of reasons! Lots of people enjoy the aesthetics of line art and computers still aren't very good at simulating that to the same degree of sophistication as people.
2D animation also degrades more gracefully with budget, and when your end result is as simple and abstract as Bobs Burgers, there's no need to complicate things. These shows are primarily dialogue driven, so don't require and aren't budgeted for dynamic scenery and complex interactions.
2D animation also degrades more gracefully with budget, and when your end result is as simple and abstract as Bobs Burgers, there's no need to complicate things. These shows are primarily dialogue driven, so don't require and aren't budgeted for dynamic scenery and complex interactions.