The time limit on patents/copyright imply to me that they are giving you time to recoup costs and enjoy the reward of your innovation. If that's so, I'd argue that over the last century the time required to enjoy innovation (time to market saturation) has gone down. Even for physical goods? I think that the radio took decades to become widespread. The ipod took... a few years?

All that to say, maybe virtual innovation takes even less time, and should have less time to enjoy monopoly? But I'm only playing your devil's advocate.