I don’t think that is a real problem.
There are a lot of units that should be pre-split before fighting, when/if the player is capable of it. Ghosts are just one such unit.
Storm already deals significant damage, considering how compact and squishy many units happen to be. I don’t think there is much room to buff its overall damage or its DPS without causing problems somewhere.
Making Disruptors less all-or-nothing might be a good change though.
The only place where Mines really need a nerf is in worker harassment, and that can easily be fixed by changing the Mine’s splash damage against workers to 35, and leaving it the same against everything else. Maybe you could throw Oberservers into that list as well, because they are the only detector that can get one-shot by the Widow Mine’s splash damage if they just happen to be close to another unit.
Assuming the goal is to prevent Liberators from 2-shotting Stalkers, the better solution would be to nerf their upgrade bonus. I don’t know if Liberators need their “full” damage against other targets though.