Basically, LOIC is a ticket to jail. The fact that it was used for so long without repercussions is that the Feds didn't care enough to do anything. That all changed with OP:Payback.
Street protests make whole streets inaccessible, and may disable access to stores, businesses or what not.
I'd also consider it a form of peaceful protest. Well, actually it's just data, nobody gets physically harmed so it's always peaceful. Anyways, you are not stealing data and you are not permanently harming the system. You basically do something the site is made for (serving requests). If you consider that a crime you could also consider telling a huge people to phone a company and complain about something a crime. I mean this certainly leads to a denial of service, because it makes it virtually impossible for others to use that service.
I for myself am a bit lazy for these kinds of protests. I actually prefer informing people so they draw their own conclusion, but I would never call something like that a crime. IMO it should be treated like a freedom. I know this can cause financial damage, but it's still not harming people. I mean every news article, every kind of information and just saying something like "Nike is child slavery" or "fast food from McDonalds is unhealthy" can make people not buy stuff there and therefore cause financial damage. In first place it's about an institution and we shouldn't consider an institution something that has human rights, because it devalues natural people.
On a separate note, I would have thought they had learned their lesson re: LOIC after OP:Payback. I guess we'll be seeing another string of arrests in the coming months.