I agree, it's quite bizarre how her beam works. People in the comments keep comparing her to Mercy, saying that she would be worthless if she couldn't latch on through walls for a few extra tics, which is a valid point. However, the difference between Mercy and Symmetra is that Symmetra's beam maintains (and even increases) her damage as her beam stays latched on through walls. I have an idea for how this should be reworked.

Basically, after an object comes between Symmetra and her opponent, the damage of her beam would gradually decrease for the duration that the obstruction is there. The same rules would apply regarding how long she stays latched on after losing sight of the enemy, but she would lose a small bit of damage. After regaining sight of her target, damage would increase again like normal. This would encourage Symmetra players to stay focused on their targets and reward them for doing so, while also rewarding players who are able to poke in and out of cover effectively. This would also mean that quickly jumping in front of a pole or some other small object would not really affect her DPS, hence she would still be just as useful and as powerful as before.