With every day time festival there is in London there will be a tiny, very vocal minority who absolutely hate the fact there are events in their nearby park, and will go on a fanatical crusade to stop them. You only have to look at that Brockwell Park Event twitter feed, or the East Dulwich Forum who have been moaning about Gala Festival on Peckham Rye which was last weekend, for months. They'll try and pin anything possible negative on the event, even though its quite normal on a warm summers day (such as litter placed beside full bins), and generally try and whip up as much opposition and fluster as they can to get the event moved somewhere that is not-in-my-backyard. Whilst it is quite funny to read, its also pretty pathetic and quite depressing to see such intolerance in our city. I get the feeling that this led to the eventual demise of festivals on Clapham Common.
I think the vast majority (most of which are silent) are ambivalent about the events, they might enjoy hearing a bit of music from their garden, but be a bit pissed off at extra traffic or having extra drunk people stumbling about not watching where they are going. Ultimately they dont mind a festival near where they live and understand they live in a city, and cities are lively places. They have more important things to worry about or are just generally tolerant of things.
I would be in the large minority camp (again most are silent) that enjoys having the buzz of extra activity in the area, and seeing happy people on the way to and from a music festival. Im amused by extra drunk people in the street, as long as they aren't violent and by and large use the portaloos provided at every one of these events. I also enjoy going to the events themselves, although dislike the fact everything suddenly turns off at 10pm, but understand at the same time. If i want to walk through the park when the festival fence it up, i do so in the 50% of the park that is unaffected.
These arguments will rumble on forever, but i dont think the events will be going anywhere anytime soon. The differences will be that ticket and drinks prices will go up (extra fencing, staff and sound monitoring cost money), volume and finishing times will go down as more stipulations are put on the licenses due to the first category above. Theyll still stand around, absolutely fuming, waving their fists at the sky and moaning to anyone who will listen though