Both the incubator for eggs of idiot broodies and broodies for power outtages and the cuteness factor. I hatch as well in the incubator as my hens do, and I've saved a lot of chickens-with-brainfart eggs over time. And broodies have saved incubated eggs in power outtages. Since the genetics stay the same, no you don't get more or fewer deformed chicks when incubating unless you're incompetent at it or have bad equipment. Then again, broodies can be incompetent. It evens out.
A good experienced broody who rears well is both adorable and priceless. Saving a clutch of eggs with an incubator, that you would have lost otherwise, also priceless.
And broodies stomp eggs sometimes, crack them too early or manage to really do them damage just about at hatch time and usually in response to some chicks having already hatched. I can save those, if I have an incubator.
Then there's the disappearing chicken (predators) that having an incubator helps with. A fox may steal a chicken but it's not going to take the incubator.
I like the whole be prepared for anything, thing.