Tank general had a weakness against mortar buggies and big number of cheap units in general (droids are often an exception because of ECM tower's existence). We thought about solutions and so we decided to give him tank bunkers. They can be garrisoned by any rank 1 unit. The emphasis was on Sniper Cannon as the combination with bunker helps eliminate some of its major weak points. A group of sniper cannon bunkers can now keep buggies away. Occupied tank bunkers are also effective vs. big hordes of infantry - get a dragon or a gauss tank in, even sniper cannon. Units can use their abilities such as war master long range mode. Besides protection from damage, tank bunkers grant +15% range. That doesn't mean they are perfect though, as they can be countered by all sorts of enemies if left without care. Normal bunkers are still in his arsenal, so the tank bunkers come extra to fill this balance gap.