How is this a bad thing, if they are really your friend and a decent person they will do the right thing, if they are neither of those then you shouldn't be around them.
they may have very strong opinions about certain things which they may choose to not speak about among friends
also giving people temp ids will over time lose the point of anonymity - people will be known by the new id instead of the old. yes, you could have id's change per topic, but even so you're trying to force something to work when it doesn't provide much benefit.
giving people anonymity will encourage them to post without nearly as much restraint with WILL lead to more arguments. i'm not sure what your "inflammatory opinions about inflammatory people" response means, but i assure you that if people on boards like 4chan could not post anonymously, there would be a lot less stupidity and/or flaming happening.
The only real issue i see with this system is that a clan could get together and via skype or some other form of 3rd party communication and railroad drama, but if you're really that much of a piece of stuff you probably don't have the friends to do that or are too stupid to even come up with such a plan.
people already do that even without anonymity; it happens more often than you expect, but with less explicit intentions. i intentionally prevent people from discussing drama in my server for this reason (and a couple others). if anything i see it happen more often than users threatening to drama each other (in drama, not ingame).
also the nickpb drama is relevant to blockland since everyone involved is a BL player. yeah, its not ingame drama, but its still something that involves the community.
basically the only thing anonymity would fix is drama derailing and allowing the drama target to defend him/herself more effectively; nothing else would be resolved. and as for "Drama focusing on negative experience sharing" as a benefit, it is specifically that that makes drama appear so "bad" - almost everything in it is negative by design.