You are making this judgement from very narrow perspective.
No, im making it from 16 years of playing the game, and basic observation of gameplay.
Its simple, the first instinct to base defense is resupply, which kills the addictive combat aspect of the game, which is one large factor of why gameplay is stale. Hence the current population.
They made one move in the right direction by removing large maps.
1 guy in a m3 should not undo undo what 5 jabos just did. Its an easy alternative to defense in air or tank. Im sure they make some sort of semi truck simulator if you guys want the supply feature so badly.
Its a gameplay killer in this genre though.