(and *only* music, nothing else since other areas have other requirements and make it easier to eg modify things):
For what it's worth, I stand by the choice to make all of our art GPL, and I refuse to relicense it under another license. We did this for a reason. I (and others before me) want people to have the right to reuse and modify our art. I want that culture of freedom. I want that world of possibilities. A caged bird cannot fly.
It doesn't hurt me if someone 'misuses' my art. And that's all this is about - being 'hurt' as an artist if someone 'misuses' our work. We choose not to be hurt, as a kindness to the world at large. We choose to make this a gift, with no strings attached. We choose to love the mistakes, and love the people making them. We're big, tough leathernecks, and our feelings can't be hurt.
Besides, even if we have it legally locked down, people are going to steal+misuse it anyways if it's any good. We can hunt them down, but it's a waste of our time. Our time is better spent making the things that are worth being ripped off. Plus if we lock it down, we're most likely to snuff out all the good and clever reuses (which are by necessity very open and public), and leave only the clandestine and cheap ripoffs.
The other thing is that every time someone 'rips off' our stuff, it's a tacit acknowledgement that they love our stuff; in fact, they think it's so good that there's no point in them trying to do better. They're kneeling at the altar of our work. In return, we can kick them as the prostrate themselves ... or we could do what we did already, which is to put our stuff under a license that thanks them for being our biggest fans.
That someone else can take the music and claim it as their own without anyone knowing is my biggest fear. That all the countless hours I put into making music will be for naught, because some cretin is going to "steal it" and pass it off as their own.
1] No license, no matter how restrictive, can prevent this. If they can hear it, they can record it and steal it. The law only protects you if you catch them, and furthermore, if you can afford the cost (be it time or money, or both) to pursue a legal penalty.
2] If your work has any value in its uniqueness, then you alone are the goose that lays the golden egg. They can steal the result, but they can't steal the ability to create - and the ability to create is the only thing useful to a potential employer. If they can't actually make the work themselves, they're useless, there.
3] If your work becomes really famous under someone else's name, you can instantly become famous by proving the theft - without even needing lawyers. The internet will do that for you - it'll spread the news of the work being ripped off all over the world, and will smother the thief's fans in the truth. At which point they will instantly be very interested in you.
4] There are two reasons people make art/music for wesnoth (or any project where they're doing it for free). "Fame" by accreditation is one. The other one is that we're making stuff so that people can enjoy it. Having someone claim they're the creator of a work does (slightly) hurt one's fame*, but it actually helps the second point. It puts our works in front of more eyes, which means more people are out there enjoying whatever beauty it has to be enjoyed. And that's the main reason I made my work, here - I make all my art here because I want people to enjoy it.
On accreditation, and the human connection:
We kind of have this funny concept that if we're credited for a work, the viewer will be thinking of us as they enjoy the work - they'll be enjoying this sort of communion with the soul that inspired the work; but ... 99% of our audience, and 99.999% of the world at large doesn't even have a clue who we are - as individual people. Even if they're reading our names all over the work, it's like we don't exist. I realized this when I looked at the credits of movies/videogames for the umpteenth time - the names, without faces, don't conjure up the creators. I want to empathize with them - I want to share the communion that a viewer could share with a creator, but I can't because I don't know a thing about them besides their name. I need a different kind of interaction with an author to care about what they wrote. When I sit down and watch an actual interview with the creators - that actually gets their humanity across to me.
Which is actually a related point: The best defense in accreditation is a good offense, rather than a defense. The only way it means anything to your audience that you, yourself created a work, is if you yourself come across to them as a human that they know. Trying to legally defend "having your name on" a work is futile if the name doesn't mean anything to the audience. The best practice is to make your persona known to the audience. It's the reason webcomics have blogs. It's the reason penny-arcade, the most famous (and rich!) webcomic ever made has their blog on their landing page, and forces users to make a second click to actually reach the comic*. Because they want to register as actual humans with the audience. The musicians I tend to care strongly about as people, I care about either because I've read/seen biographies (beethoven, mozart, stravinsky), or because I've directly read/seen interviews with them (Trent Reznor, many others). I care about the musicians on this project because I know them.
Defending your name on something ... doesn't really do any good, if you don't already do the one thing that actually matters, which is making yourself familiar as more than just a name, to your audience. You need to put yourself inside their monkeysphere.
I'm going to link that again, because it's such a staggeringly important concept:
http://www.cracked.com/article_14990_wh ... phere.html
Another funny anomaly is that legal protection for accreditation doesn't change in response to the scale of fame. If you never become famous, no one cares if your work was made by you (because they don't know you, see above); as far as they're concerned, even if your name is all over it, your work was just made by "some person" who happens to have your name. If you do become famous, then it doesn't matter how protected your work is, because you're so famous that everyone will know who really made it, anyways. No one can cover a major band's tune without everyone knowing that they're covering that tune - it's ludicrous to think otherwise. Plus, if some nobody composes a tune and has it stolen by some famous artist - that nobody has a one-way ticket to stardom the moment that 'theft' gets found out, especially in the days of today's internet when word travels so fast and wide. People will want more, and they can only get it from the goose that lays the golden egg.
* Anyone studying classic marketing would view this as capitally insane. Make it that much harder for them to reach the comic? - they might leave! Penny arcade is evidence that's it's more on the lines of genius.

