I'm a great fan of bottles. But then I do drain each and every one that I take, as I lose loads of liquid.
Those wee plastic cups don't give me nearly enough, so at races where they're offered I have to stop completely at each drinks station and drink two to three cups full.
But I agree, there were loads of runners who just took a couple of sips and discarded their bottles.
Perhaps the solution, at bigger events like this, might be to offer a choice. Or alternatively smaller bottles.
But please, no return to just half-filled cups.