Breathing in space would have one huge advantage for the entire franchise: Things could finally look different!
Let's be honest for a moment. Fights in Dragon Ball always look the same. If you take a random person, who doesn't know anything about the series, and you show them a couple of fights... they would NEVER be able to put them in order.
For example, show them Recoome vs. Vegeta and Piccolo vs Android 17. Then ask them who is stronger. They wouldn't know. How could they, the fights look exactly the same. Piccolo and Android 17 are on a completely different level, but you could never tell that just from looking at the fights.
Who is stronger? This guy

or this guy

I think you get the idea.
Breathing in space would solve that problem. A couple of things the writers/animators could do in that scenario:
- Have people crash through planets. How many times have we seen fighters being thrown into mountains, just to come back with a huge Ki explosion? Do the same thing, but with planets.
- Show planets exploding left and right from random Ki blasts.
- Have a zoomed out shot with fighters jumping from galaxy to galaxy, to show how insanely fast they are.
- Have a normal shot of people fighting, then zoom out to a galactic level to show their impact. Something like this:
What do you think?