Sure, if we are talking about haxors who never run out... But then again, Morel didn't really manage to do a whole lot in this battle, did he, despite never running out (although he could do jack shit after stupidly losing his pipe to Pouf of all opponents; a huge weakness if any)? I admit we don't know yet enough about Killua's power to judge it sufficiently. And no, I very much doubt he can cure everything by sucking electricity. But if he can recharge his electricity based nen that way, then it's all good and nothing bad, as the alternative would be to rest like any regular person. I'm sure he can gradually extend the time he can wield it as well. Electricity also doesn't seem to be hugely popular among nen fighters, which means few opponents would know how to defend against it; even a monster like Youpi was helpless, although being a monster he didn't take too much damage.