Uh, yeah, that's because siege tanks and thors are anti-ground and vikings and thors are anti-air.
There won't be a balance patch. You just as easily say "Protoss, start using immortals, stalkers, void rays, and Phoenix because that counters everything in the ____ arsenal!" or "Zerg, start using hydras, ultras, corruptors and brood lords because that counters everything in the ____ arsenal!"
You do.
http://wiki.teamliquid.net/starcraft2/Protoss_Strategy
Believe me, Terrans have the most accessible tech. Hydras counter that whole protoss combo, as does MMM or even more so, mass marine. The Zerg combination that you listed is completely impractical. The Terran mix is a modified Mech ball, a common strategy at higher levels. The Vikings are only used as a counter to brood lords. If the Zerg doesn't have those, the factory units literally counter everything the Zerg has on the table.
Btw, nice pylon.
Back on topic, the SC2 forum is currently littered with complaint about Zerg's UP or Terran's OP. TvZ's brokenness is no exaggeration. The only way for Zerg to win is to starve the Terran, or get Brood Lords to forget his turtling ass. However, against a Terran who doesn't suck, the battle for map control, which Zerg rely on heavily, is much more difficult. Well, I can try for a baneling bust, but at Platinum, it doesn't work very often.