I think that taking a drink to the dance floor is just bad manners. Buy a drink, drink it and then get back, that's how it should be done. If someone goes to the dancefloor with a drink and he also can put it down on a proper place after finishing it, it's ok. For all those idiots who don't understand that dropping a glass or a bottle on the floor, I have only one thing to say: "Stay home because your mother is propably used to picking your **** up."
I agree, I have also seen a few nasty cuts from bottles on the dancefloor. Last year in Ibiza I see a horrible one, In Priviledge, You know the bit in the middle of the dancefloor on the terrace? The platform, well there was loadsa people up there and a guy got pushed off, landed on his back. He was so drunk/high, I helped him to his feet and asked if he was ok, he said yeah and his mate went to pull him back up to the platform, wasn't till he was half way up that my mate noticed the blood squirting from his side. He had landed on a bottle and not even realised! He was quickly dragged away.