Upfront Payment vs Subscriptions

There is a movement to have one upfront cost rather than pay subscriptions.  Personally, I like the upfront cost.  I hate the trailing subscriptions.  Arguments against are that you constantly need to find new customers.  But aren't you doing that anyway?

For communities, there is no marginal cost for incremental users.  In fact, there are benefits.  Metcalfe's Law states that the financial value or impact of a telecommunications network is proportional to the square of the number of connected users of the system.  The system is exponentially more valuable as the population increases linearly.  No marginal cost plus exponential benefits - why would you kick users off?