Sometimes the name you call something can make all the difference in how it is perceived. It certainly won't hurt for you to try this different angle. So are you charging a dues? If so, is it really a financial necessity for your group? If not, get rid of it.
When the elementary group I belonged to had parents fill out volunteer forms, they did it at registration and open house, so the parents filled it out right on the spot and turned it in. Sending stuff home to fill out and return isn't necessarily the best option. It's too easy to lose the paper, forget it, or just ignore it, and then you have to rely on your child to turn it in to their teacher.
This is my first year as pres of a pretty active PTO (though no one would take the presidency). Every parent is a member of the PTO. There are very few things on which we vote.
At the beginning of the year, we always send out the membership brochures with volunteer opportunities. We have a small return of these forms. I have heard parents complain about the "membership" and how that creates a feeling of that dreaded "clique" word. Despite many flyers, etc to the contrary, people think they cannot attend meetings or be involved if they've not sent in the money. Even worse, others are afraid to "join" the PTO because they think that means they have to volunteer.
I was thinking that instead of having a membership drive, we do something different this year and have a PTO Booster drive or something similar to that. Opinions? Thanks!