[sodomizer]

I sympathize.

However, I think the most successful WordPress plugins are free, because most WordPress sites belong to dabblers. They are already paying for hosting; in their view, software should be free.

As leverage however, having a successful WordPress plugin can get your name out there, build up a ton of links to your URL, and get you contract gigs. People are making this work. I doubt you're going to make any money from the plugin alone however for the reasons you mentioned.