Sometimes people don't understand exactly how a statutory road association works, and they may be swayed by misinformation. It might help if you could arrange an informational meeting with once of the MARA Board Members in attendance to dispel their fears. (Depending on where you are located and when a meeting could be arranged, I might be willing to do that.)
Another possibility would be to try to get a couple of key people to attend MARA's fall conference. That's an excellent place to learn how a Statutory Road Association works so you can decide whether that's the best option for your road. If you can sway a few people who have influence with the rest, that may be all you need to do.
One other thought - if there is someone who lived there before other houses went in, who perhaps maintained the road themselves for their own use for years, it's understandable if they object to contributing to keeping a road passable for others to use. Our road association decided at the outset that a family that had lived there long before the land was subdivided should not be compelled to be a member of the association. We notified them (as required by statute) of our intent to form a road association, and they attended the first meeting, but we gave them a choice of whether they wanted to be a paying member of the association or not. They chose not to. We have never charged them dues since, but they are welcome to come to meetings. They've been good neighbors for years, acting as an informal neighborhood watch service, plowing people's driveways, etc.