Powers have nothing to do with it. If Power=cool, then Goku would be cooler then Bogart. Jubilee would be cooler then Bruce Lee. Aquaman would be cooler then Hit Girl. Batman is cool because it's interesting to see heroics not based on the impossible, yet still in the realm of incredible and obviously fictitious. Its interesting to see heroes who have to fight against villains who don't have an advantage in overwhelming power, but in the simple fact that destruction is easier then protection, and being moral is harder then being evil. In fact, Batman and Superman, the most blatantly overpowered hero out there (In theory), have a lot in common. Id even say that Batman is like a Superman without powers. Both are characters that are rather one dimensional in order to focus solely on that dimension. Batman just focuses on that one dimension without powers.