With regard to the name change. . .
In terms of branding, I first came to this coin BECAUSE of the name and design. It just looked cool. After spending some time with the Doge community (which is fun, light, and glib), the idea of something a little more "sober" attracted my attention. But looks are a terrible reason to buy altcoins, so I did some research, discovered it IS a serious coin, and bought in.
I believe the name and branding are just right. There's a little bit of mystery, a little bit of seriousness, and a whole lot of mathematical rigor. If Bitcoin is your father's Hyundai (staid, efficient, reliable), Darkcoin is a Tesla (cutting edge, futuristic, sexy). You cannot possibly hope to find a name that gives you a more enticing draw.
Change the name, even to some of the good coin names suggested in this thread, and you lose its most powerful draw (at least initially): this coin is DIFFERENT. Name it Freecoin or Seriouscoin, or something tame, and you've neutered its sex appeal.
If that was all the coin had going for it, then none of this would matter. But we know different. And in the end, the community will likely make the best case for its use, and we'll have to defend against accusations that its only purpose is for all things illegal. There is no question that, no matter what you name it, you'll have that issue because of the coin's transaction anonymity.
There are precedents for this. Pirate Bay, Bittorrent, Wikileaks, and, before them, cassette recorders, VHS players, and MP3 files, all have been accused of serving only one purpose: making illegal activities easier. But just like each of those tools have proven effective for numerous legal and beneficial purposes, we'll be able to point to positive uses for Darkcoin.
The name can't make the case for us. It can only draw people to the community. WE have to make the case for what it can do.