In saying that, I see no point to DRK, it is a variation on everything else.
Let's split "the point" to DRK into 2 categories:
- monetary
- technological
Monetarily, there are generally 6 accepted "properties": portability, durability, divisability, scarecity, un-consumability and fungibility.
Bitcoin exhibits all of these except 1: fungibility. So there's the first "point" to DRK - it adds fungibility where there is a problem in bitcoin.
Technologically, the "point" to DRK is that it's technology is designed to support the fungibility requirement as optimally as possible. For example the coins are pre-mixed while in the wallet. This is a very different approach from attempting to "hide" individual transactions right at the point of use because it places the emphasis on supporting a monetary property rather than a technological one.
As far as "the point" to DRK relative to other anonymous coins, there are probably several but the one I would pick out is that the others are almost exclusively obsessed with pursuing "anon-technology". This is admirable but it isn't where the value or marketcap comes from. Most of it comes from a monetary premium gained from adoption as a monetary medium whether that be a as store of value or as a token of goods exchange. So pursuing monetary properties over technological ones will always produce more effective returns in terms of value.
If you look at the history of crypto-currencies you can see that first mover advantage combined with a trusted development plan thats seen to be delivering is an almost guarantee of market supremacy. Even if others come along which improve on your tech, they don't do anything to your marketcap unless you make some kind of catastrophic mistake. This has been true for so many cases - bitcoin, litecoin, NXT, Bitshares, Peercoin etc. They've all had both clones and originals in the same market sector, none of which really challenged their market position.
I'd probably even include Monero in that category because it was one of the early cryptonote coins that has sustained its position in the top 20 and it has a respectable 2M+ cap. So it's not a sh*tcoin. It's also a good hedge for DRK because it uses a completely different algo, however the fact that Darkcoin is compatible with Bitcoin's API is a huge commercial advantage for it which will help to consolidate its position IMO.