Still cannot understand why would the market cap matter. It's like LTC have 6x more coins at the moment. Isn't that pointless?
It matters because every investment gets effectively, a percentage of the market cap. You are buying a piece of the total supply. There aren't that many DRK in the grand scheme of things. 4,617,852 DRK is much smaller than most of the other players. What someone has to pay for your coins is directly related to the available supply.
If another coin was also around .0058 BTC but there were 10,000,000 of the coins, you would be getting less value buying in.
If the total supply of coins isn't large that isn't necessarily bad or good. It only means that's how many there are. That said, you have to know how many there are and the price of the coin to understand what value that you are getting.
It matters to me each time I add an mn what percentage of the network I am at and what percentage of the coin supply I have. Too much and I'm taking too much risk. Too little, and I can't make a difference. I have no interest if I can't be part of the movement of the market.
Lastly, the market cap is indicative of the total value of the coin. Apple Computer's market cap is 618.55 billion USD. You can't look at the share price of $99 and make a decision on the share price alone. The market cap divided by the number of outstanding shares in the company is what prices the shares. It also defines the value of what you hold after you've bought it.
edit: I edited that last paragraph for clarity