They are quite organized, it's pretty hard to be disorganized, when you only have 2 main developers, and 2-3 occasional helpers.
I think the biggest hurdle in developing this version was actually the choice of using libRocket to script the UI with. Turns out the lib is very slow, and it needed lots of work to get working properly.
When this game was founded, about 7 years ago, Quake 3 was at a pretty big peak. The original goal was to make the next big competitive FPS. Though that didn't last too long, even though the scene is still largely very competitive players, there's no big tournaments for the game. Another thing to note, is that Warsow's engine is actually based on idtech 2.
Yeah, the game right now I don't think is that good. I was talking with the developer and he's planing on doing some big gameplay changes. I really hope it turns out good, that game has a lot of potential.
I personally think it's better to break backwards compatibility if you're removing or changing something that was bad in the first place. Otherwise, there is no need, and thus it never breaks. Much like in the case of your list of non breaking programs.
The cool thing :target allowed was those css3 only lightboxs (http://tympanus.net/Tutorials/CSS3Lightbox/). I might play around with this method and see if it works as well.