Vanishing camo in its current state on the Jagd Tiger would not be cool at all. You finally get a good surround or flank and the toggle on and off just screws you over in trying to kill it.
Tank camo needs to work like the sniper camo and have a cool down.
Tank Camo is actually exactly the same as Sniper Camo, it's just based on when you last were in combat instead of amount of shots fired/cover (because the game engine doesn't allow for cover affecting tanks).
I never said adding it would be a good idea...I just said it was there lol.
The reason why you see tanks cloak in the middle of "combat" is that they need something actually shooting at them to decloak them, you can also use the new increased spotting range on recon planes and scout cars to see cloaked units.