I think that's a bit retarded.. in WoL, the only spellcaster for the Zerg is the Infestor and FG is good because of it's ability to lockdown.. If invisible units (Ghost, DT) cannot be affected and if the detector is down, there's essentially no way to detect/kill them?

Raven seeker missile upgrade I reckon could use a shorter cooldown but removing it altogether will break the way Ravens are supposed to work.. They're a support unit and something you use to help your army.. What's gonna stop a player from sending a Raven to seeker missile your mineral line early game instead of a Banshee (maybe a minute or two later) but that's about it.. Meh..