To be honest I don't get why it is so crucial, but let me explain how it works.
If I would have bad intentions (and skills) I could destroy 10 coins so far. I am operating pools almost a year now for 23 coins. My pools are fast and stable that's why people like to mine here.
I would say I am securing coins networks with my pools because single farms and haters cannot get enough power. You can say my pool can be DDOSed and of course you are right (although my pools are DDOS protected in some extent) but other pools can be DDOSed as well - whats the difference? They can do it for 1 or 2 or 3 pools without any problems. There is very simple solution for this - if DRK price will go up more pools will be opened and people will spread hashpower naturally.
feeleep
Feeleep, I think you're providing a great service. I guess the main point is that we want these coins to be secured in a decentralised, trustless manner. Even though you might be a completely trustworthy pool operator, the very fact that your pool has > 50% of hashrate for a coin means it's no longer a trustless scenario. So, all power to you as a pool operator, but for the health of these coins you need competition.
[edit] Yeah -- what TanteStefana said.