Now I haven't been everywhere is Europe but I have been to many places. My experience is that you can't just go wandering down any street drinking booze. Most places I have been to allow outdoor drinking next to a bar, pub, etc to expand the area and allow for socializing outdoors.
My experience in Europe is totally different. I've absolutely been able to take alcohol and walk down any street without anybody looking twice. I've done it plenty of times and nobody has ever given me a dirty look. Picnic under the eiffel tower? Definitely bring a bottle of wine. Heading to a concert? Bring a beer for the tube ride. Heading to the beach? bring a six-pack. The only drunken hooligans I saw were the football crazies and the after-the-bar-closes crazies.
My favourite public drinking experience from my time in Europe is when I walked the Camino de Santiago. Along the path there is a "wine fountain" where pilgrims are encouraged to fill up their canteen's with wine to give them strength to walk the last couple of kilometers. (google "bodegas irache")
Honestly, it's one of the things I miss most about living in Europe and because of that I've basically stopped caring about the public consumption laws here. In summer, I often stop into a liquor store and pick up a tall can or two with the girlfriend and walk around downtown with it, watching the buskers, enjoying the sun. I'm not being a delinquent, I'm being European.