I though the same thing recently. It was a necessary balance at the time because Tracer was dominating the meta so they made her less good against tanks, but now tanks dominate the meta and Tracer feels unplayable often times, so I think bringing her Pulse Bomb damage back up would be a good idea.
The op is not really accurate, the nerf was absolutely needed, when the game was in the dive state. But the issue is, with the countless buffs to her “counters”, that still are rather terrible at countering her and the introduction of the ultimate counter (Brig), that only after armor nerfs finally isn´t throwing to pick Tracer vs her. Then yes indeed in this age, it wouldn´t hurt to give it back, when tanks are dominating with healers. But the issue is, why not give her other things than damage on pulse bomb ? Like a couple more bullets in the mag, 1 more damage or -1 armor piercing rounds etc.
I can see other solutions, that might make a better solution, but the one shot potential on tanks as a squishy mobile flanker, was really a weird one.