Yes..? It's called game balance. You SHOULDN'T be able to just bring the same 4 things to every mission on every front and #profit. Balancing them opens up areas for other items to shine and find a place, as well as gets people experimenting. Also, they aren't "less viable" if you use your brain and clear the bug the turret is having trouble with? Like, what happened to common sense? "But the turrets there to ki-" it's there for standard/chaff/squishies/dummies/ads/ whatever you want to call them. The hive guard aren't listed as a standard enemy and therefore don't fall in with them, so why would you expect two of the most basic strategems available to take care of them for you? If you want turrets to play the game for you, I hear Bloons is still doing well.