You're definitely on the right track. Your involvement gains are great. Nit surprised that an emphasis on fun has paid off for you.
That said, there's usually some truth to be learned if you start hearing the same concerns from several different directions. I'd caution you against a "if someone wants to do it, let them" philosophy. That will lead to a real mishmash of schedules, events and volunteer needs.
Part of the leadership challenge is helping to guide the direction of the organization. What are our priorities this year? How can we best utilize the limited resources (volunteer help, money, attention of parents, schedule space) we have? It's a delicate balance between strategic planning (which means sometimes saying "no")and keeping enthusiastic volunteers on board. That's a leadership challenge.
One of the common results of a "let them do it" philosophy is a whole slew of kind of OK events. Perhaps you can work at creating a couple of real signature events for your group. Couple of nice results of doing that are: 1) as those events become "famous", they often attract volunteers, because folks like to be associated with success; 2) A large, signature event is a great place to funnel new ideas and energy. Example: if you have a signature fall fair, then that mom who suggests starting an art fair for the whole school can be funneled to starting an art fair pavilion at the fall fair. Makes the fall fair better, doesn't clutter up the schedule, and rewards new-idea mom.
I am president of our PTO for the second year. Prior to my presidency, this PTO was non-existent in the school. We added a lot of events and activities for the kids last year. Over the course of the year, you could see attendance was up and up, due to the fact the word was spread about how much fun these were for kids. Now the new year is upon us and I am back added just a few things to our plate. I have had complaints from folks that we are doing too much. The problem is that I have volunteers already lined up to do these things and I am under the feeling that if someone wants to do it, let them. The moment we start shutting people or creativity down is the moment that your organization is done. Please note that in past years the number of those involved with the PTO has never climbed past 10. We now have over 30 volunteers and the teachers are even stepping into this and getting involved. Does this sound like a problem anyone wants? I thought we were supposed to be going in this direction? Need some advice.