Because batboxes are expensive in the long run. Every batbox requires 6 Tin Ore, 6 Redstone Dust, 2 Copper Ore and 4 Rubber to produce. We are looking at TENS of stacks to transport energy anywhere far.
How much does cable cost per tile? 0.25 Copper Ore and 1 Rubber. Or 0.125 Gold Ore and 2 Rubber. Or 0.125 Iron Ore and 3 Rubber.