Plasma storms are not a waste for SB as it prevents its destruction by bombers, one of the number 1 killers of starbases today, especially Orkulus. Magnetic Clouds can offer their own bonuses to starbases, not so much the Advent's as it relies heavily on antimatter abilities, but for Argonevs that can construct fleets are particularly efftive their in that magnetic fields can defend your fleet and your starbase from powerful Cap Ship AM abilities (Missile Barrage anyone?)
Also Asteroid Fields and belts make all ships miss a certain (or higher?) percentage of the time. Not sure at the moment of the exact value.