I have seen it. Twice. Over at DCA. I can't tell you how much they drunk or their ability to hold their liquor. What I do know is that a gal, who was swinging pretty high with her crew of ladies, threw up on Soarin', so they had to take a train down while they cleaned it up. The other place I saw it was right outside Cove Bar where some dude was laughing in his drunken state and then bent over the edge and threw up in the water. Glad my kids got to see that.
I haven't been to DLR hundreds of times. But I've been there enough to see what happens when people drink too much. I just don't see a reason to introduce it more widely....except for Disney to cash in. I guess it'll be worth it if ticket prices can stay lower because of the profit margin Disney makes on alcohol, but we all know that's not going to happen.
I just feel like, there are SO MANY places to buy alcohol already at DLR. Adding it into Disneyland isn't going to make a difference at ALL. Those drunk people you have encountered could just as easily walk into Disneyland vs. DCA and go nuts in there. It's not like Disneyland has a magical fence to keep out all the people at the resort who have had alcohol.