I may be missing something important, but maybe someone can help.
Normal POS (PPC, NXT, etc): If you leave your client open and unlocked for staking (or minting, forging, whatever they call it), you contribute to the security of the network and are paid for your efforts.
DPOS: 100 trusted delegates are paid to maintain the security of the network. Nobody else has any incentive to leave their client open, since they earn dividends whether they do or not. In fact, for their personal security, they should put most of their holdings in cold storage.
My (probably naive) question: is this bad? Are the (n-100) users who put their tokens in cold storage free riders? Would they be contributing to network security if they had their clients running?