I don't think it's that simple.. Are new people just discovering Darkcoin now?? Doesn't seem likely. Or, did people not think it was going to progress to this stage? Or, is someone just using the release schedule to pump the hell out of Darkcoin?
It's just that most people in altcoins have a very short focus in terms of investment horizon. When nothing happens for a few days or weeks they lose interest. It's like watching TV and getting bored with the content, wanting to change the channel. Just look at the "sentiment" in the last few pages prior to exiting beta and entering release candidate status:
1) people noticing that activity in the thread is lowered = quick to declare that the coin is dead
2) people noticing that the price trendline is slightly negative = quick to declare that the coin is dead
3) people noticing that other coins are more "interesting" with their pumps and dumps = quick to declare that the coin is dead
That's it, in cryptocoin market, patience is your best friend. If you're not up to it, it's better to use money in other business.