Fun while it lasted

PhillyCarShare just sent out emails stating that they'll be eliminating their "Basic Freedom" Plan, which had no monthly fee but higher car-rental rates. Now everybody will pay a $15/month fee, and pay the lower rates (costing about $2/hr less). But since I only typically use PhillyCarShare for two hours or so a month, that's a big increase in my cost per hour.

I have until Wednesday before the switch goes into effect. I'm pretty sure I'll leave (the email even included a link for canceling membership, so they clearly know some people are going to be unhappy). I just can't figure out if this is purely an attempt to increase their revenue (and the number of hours per month their cars get used), or if they have some other reason to want to get rid of their occasional users...