Reducing the Spitters has hardly had any impact on them at all in the game. They can single handedly turn a fight around, and if the whole enemy team has them? Good luck. :p They seem like the go-to pick for almost any character or team composition, and have had more of a negative impact on the game than any other power so far.
They can make characters vulnerable to devastating attacks that they wouldn't normally be vulnerable too, slowing some to a total standstill.
They do a lot more damage than you'd think, especially because you have to destroy them up close as a majority of the cast. Multiple plants worth of damage quickly add up.
They can hone in on your from frankly ridiculous distances. A single slowdown effect can ruin your gameplan by greatly reducing your jump distance and general evasion.
Their ability to capture gems is unparalleled. Many times I see even expert players just stay away from a gem group covered in plants, knowing they can't do a thing. If even the experts give up just like that, you know something is seriously wrong.
So they seem a bit essential no matter how you slice it at the moment. How could they be tweaked so that they become fair, fun to play against and yet not be nerfed into the ground they grew from? Be creative! The more we come up with, the more hope we can have of weeding them out at least a little in season 3.