You couldn't be more right on - if my kids played with the rope in that area and you would have said something I would have pulled them by the ear away from the rope AFTER apologizing! For the parent to give you a dirty look was as rude as the kids. I know my kids can be a pain, all kids can be - it's ones that listen to their parents that you can deal with.
As for the teens on the ride, just UGH! I had that happen on Star Tours - after the ride (when my kids were little) I told the teens that they ruined the ride for everyone on there and to go somewhere else - they laughed at me - just rude - I can't stand it.
If I see a gaggle of teens I go to another ride - I won't even put myself in that situation again.
Someone said here to teach Disneyland etiquite - maybe we ought to print out some business cards with those etiquite rules and hand them out