Why must these sorts of contributions always be BSD licensed, what is wrong with public domain?
The public domain is where things go when their copyright expires. In most countries -- including the United States -- there is no legal procedure to dedicate something to the public domain. You can claim something you wrote is in the public domain until you're blue in the face, but it's not. You still own the copyright on it.
The closest you can get to a public domain declaration is a bare license: basically a license which says "Copyright 2012 by me: I give you the license to do whatever you want with this." The problem with a bare license is that if your code doesn't work right, people can (and do) turn around and sue your pants off. Because -- remember -- the work is not in the public domain. You own it and are responsible for it.
Thus we get to a BSD-style ("academic") license. At a minimum this license says "Copyright 2012 by me: I give you a license to do whatever you want with this as long as you agree not to sue me if something doesn't work".
Always use, at a minimum, a BSD-style license. Public domain is a fiction.
Otherwise, I agree, there are a fair number of inaccuracies in the GP [SeanLuke] comment.
(I ask because I'm curious, not to further a debate about PD).
But I'm particularly interested in Bernstein's ad hominem broadside on Rosen for stating, while general counsel for OSI I believe, that public domain dedication is unlikely in the US. Rosen is "only a lawyer" according to Bernstein -- who I might add is "only a mathematician". Though you have to give him props for representing himself in Bernstein v. Commerce.
I myself think that Rosen's conservative position is the right one. Even Lessig's CC0 dedication is couched in tons of careful "we're not sure if this works" verbiage. At any rate, presuming this is unsettled law -- and it seems to me that it's pretty unsettled -- that alone makes it unwise to be attempting a public domain dedication.
I'm really not interested in the conflict between the OSI and Dan Bernstein. I'm just responding to your comment.
Pretty sure you're wrong about PD being a "fiction".
Well, you did directly cite an article, about a third of which is devoted to smacking down someone with more cred than himself.
That being said, my comment about PD being a "fiction" was overly excessive bomb-throwing, I admit.
But, can I just add two things: that's about as specific a legal argument as I've ever seen an engineer (or mathematician) make, including chapter/verse citations to actual court decisions. Not only are you mischaracterizing it, but you might also take a moment to be specific about which parts of it you disagree with. Why should we be interested in how we feel about people's interpersonal conflicts? Bernstein is right or he isn't.
Second: I didn't call you out for bomb-throwing (that would be hypocritical in the extreme). Can I ask, how much of your original comment do you still stand by?
And, in many cases, everything. SQLite users have had this issue in the past: http://www.sqlite.org/copyright.html
Which are generally MIT/BSD variants.