What coins do you refer to here as being technologically superior to Bitcoin? I know that there are lots of coins out there with features like smart contracts, POS, smart property etc., and some of them may succeed. The main difference between them and DRK, is that DRK has just focused on improving one feature people already like about Bitcoin, anonymity, and it works right now.
Peercoin was the first major 'revision'. It had an an economic model which was thought through and much more focused on a particular role - i.e. being financial 'backbone'. This was reinforced by its high transaction fees and hybrid algo.
Then there were improvements in the algos themselves - Asic resistence, multi algo, service layers, efficiency and retargeting revisions, gravity wells etc.
What I'm saying is that having the most advanced technology isn't what gets a coin its valuation. Being seen as an 'original' certainly would appear to contribute and that's probably where DRK is strong.
Ok so on paper Peercoin might be have some better features, but why should I use it instead of Bitcoin? What does it offer me? I really don't know, even though I've known about it for ages I've never read anything or had someone try and convince me to use it. Most people like me (not a trader) have no interest in Peercoin, so I'd reason that it is traders who are keeping the price up.
Darkcoin on the other hand, I could see why I should use it straight away, anonymous transactions. That is DRK's killer feature. Anonymous transactions is a feature which is very desirable, and will mean that people who aren't interested in trading also enter the currency to actually use it as a currency.