Fees secure the blockchain from malicious attacks. So you'd rather pay a fee rather than have a busted blockchain that got to 1 terabyte because some kid found it funny to run a script with 1000 bogus transactions per second.
Remember that you pay for your hard disk space.
50$ / 1TB = 0.05$ per 1 GB of blockchain bloat.
Multiply that with the number of users to find the collective cost of bloat.
Standard blockchain fees will apply the additional premium 'anon fee' that XC and DRK charge will not be applicable to our anonymous function
edit: Also if you read the OP, you will notice why we chose PoW/PoS hybrid and also included fee for standard tx, this is to ensure maximal blockchain integrity. We take security very seriously but you have our concept misunderstood.
It is my understanding that DRK uses 20% block reward (from new blocks generated) to pay mixing nodes while XC uses tx fees (as it can't generate coins with new blocks due to being PoS).
DRK also uses collateral so that misbehaving or DOS attempts are penalized by losing money.
If you allow me a small correction. PoS blocks *do* generate new coins (that's how the "interest" is getting paid).
Now, regarding DRK behavior, although I haven't read the code so what I'm going to say is just the way I understand it, how can the system identify a misbehaving node? by the IP? because there is no other way (unless coded to give unique identity to each wallet - which in turn means that wallets are now having a full identity ) to identify a wallet, only the IP is logged (and scored accordingly). Maybe I will study more about that, once I'm done with the project I'm currently doing
Again to the best of my understanding, there are two or three levels of misbehavior... the sender of the money who can lose collateral if he does something evil, the node which can lose collateral for not doing the transaction correctly, and the miner who may try to forge which masternode gets paid in which case his block is orphaned and he loses the entire block.