It's less that the energy consumption is too low (it was actually increased already - block dig cost went from 30 MJ to 50 MJ, IIRC), but that energy generation is being increased exponentially by other mods that are trying to one-up each other to stay attractive to players.
- Railcraft's solid fueled steam boilers produce anywhere between 10-20 times the energy from charcoal than classic Buildcraft does, 20-40 times as much when using coal, and the coke oven allows you to double the fuel value of coal again on top of that.
- Thermal Expansion lets you make significant energy out of netherrack, a block that's about as valuable (and plentiful) as cobblestone.
- Forestry doesn't even bother with numbers and just generates infinite fuel out of thin air, while at the same time allowing you to hook up IC2 solar panels to electric engines for yet more neverending energy.
Try fueling your quarries with classic Buildcraft only. That means stirling engines producing 2,400 MJ per unit of coal, not 40,000-80,000. Or lava-based engines running at 1 MJ/t instead of 4 MJ/t while requiring massive cooling - with pumps, sir, not aqueous accumulators. In fact, the only thing in classic Builcraft running faster than 1 MJ/t is running off a rare, very much finite resource that you have to put effort into procuring, refining and moving around. Now consider providing 50 MJ/t to a quarry in that environment... suddenly that becomes a very serious project, not something you throw down effortlessly on day one.
Also remember that the quarry, too, must step up its game to compete with other mods introducing cheaper, easier methods. Mining turtle, anyone?