Once again, you did not get my point, it is not about balance it is about unit design.
Zerg is about swarming. It is by design. If you get rid of those type of spells then you will remove part of what makes the game rich.
You do not want the races to be redundant or similar.
So go on, nerf whatever you need if there is a balance issue but please do not impact game mechanics.
I could say the same about vortex spell removal.