Brigitte being able to stun from 20 metres away would be the most OP thing ever.

Every ult would get interrupted everytime. Pharah would be cannon fodder. Reinhardt would be unable to use charge. Etc, Etc, etc.

Right now, the counterplay to Brigitte stun is to zone her. If she gets close to you, you know you’re going to get stunned. It’s how she operates.

Swapping it to a ranged ability removes that though and changes how she plays completely.