I'm not allergic to silicon dioxide, but a lot of people are becoming aware of the dangers of these nanoparticle fillers, and are trying to reduce their exposure to them. Most pharmaceuticals nowdays contain silicon dioxide or titanium dioxide etc. The studies are pretty clear that these ingredients aren't good. It's a huge problem because of how widespread the use of these nanoparticles is. They're everywhere. Nevertheless, a lot of people are trying to cut out these ingredients in their lives.
You should consider trying a mix without silicon dioxide. It might work. If it did work, it might be a good marketing strategy to advertise products with none of these fillers. People may even pay a premium for that.