Things such as Spider mines, and nuking were almost unheard of due to their lack of usefulness. Over the last 5 patches to SC, and the introduction of BW, people have been forced to use the previously less known techniques, like the use of spider mines to counter Dark Templars. The upgrading of the Carrier's power is just another example of this. People were forced to come up with tactics to counter mass Carriers. Wraiths now did 20 damage.
Lockdown is now a word most people understand.
Battlecruisers could and can still also hold their own vs. Carriers. Well, an observer that can't see is as useless as none at all. If you don't want to risk your Wraiths to destroy the Observers, then blind them. Protoss have equal units, as well as psi storm and heavy damage units such as Scouts and Dragoons to take down Carriers. Zerg were forced to make use of plague and ensnare.