Yes, it does help a lot! At least at my school, we always went to volunteer vision screenings or optometry conferences. We also helped each other a lot on studying for classes and preparing for the application process. Also, a lot of pre-optometry clubs provide a sharing of study-materials for the OAT which is really helpful and cost effective =P!
And especially if you try to get a high position in the club, I think it would be a major asset for your application/resume. Schools really look at your leadership positions. You should definitely join. It gave me something to talk about in my interview and in my essays.