Just as an added note, Spiders tend to lose a lot of their frightening potential come late game when units aren't afraid of piercing damage, and are toting enough firepower to make them evaporate, green cover or no.
I am not sure if you are commenting on 1v1 or team games but I think that this concern is less apparent in 1v1. There won't be that many units that are not afraid of the warp spiders' piercing damage and the large amount of space on the maps means the spiders can use their superior mobility to do something useful besides engaging in a one-sided battle (e.g. shooting a regular termies or some other late game unit).




You need to get to that part of the game first and naturally they are better in vacuum, they also cost a lot more.
