A tank with the power of 2 tigers is a fair trade-off for cutting off income for the rest of the game, and you can't exactly dominate the whole map when all that power is contained within one single unit. It can only be in one place at a time and only shoot one target at a time.
The problem is when you call in the Ace right before you do an all out all or nothing attack. Who cares about income when you just completely wipe out their army. A tank with the power of 2 Tigers is insane.