Thanks for your comment Digital_Quartz.
For some games it might be possible to move substantial logic on the server. These may be: 1) games where there are no strict lag requirements (e.g. adventure games, puzzle games like Puzzle Pirates); 2) games where the needed bandwidth for each client is small and the client does some prediction and/or interpolation.
It is true that you have the additional cost of the server (which would need a lot of bandwidth _and_ computational power); but this cost might be more than compensated by the additional income due to less "piracy". (Or it might not.)
The perversity of nature is nowhere better demonstrated by the fact that, when exposed to the same atmosphere, bread becomes hard while crackers become soft.