So, I try to stay out of mask conversations because it always just opens a can of worms. That said, I am a pharmacist. I vaccinate people daily. My family (those of age) is vaccinated. However, do I still wear a mask in public? YEP. The people coming to get their shots 99% of the time are not wearing masks and have to be provided one in order to receive their shot.
In my opinion, the reason you can't go to an "only unvaccinated" must wear masks is because too many who should won't, which is technically where we are at in my state. Only those vaccinated should be walking around with bare faces, but that's not at all what happens. I will sit there and counsel someone on their second shot that they qualify to remove their mask in 2 weeks...and then see them in the store shopping 20 minutes later without them. Unfortunately, this mentality is what is allowing so much mutation with the virus. The more hosts it jumps to, the more mutations are able to come out. If we could rely on the unvaccinated population to wear masks, the discussion wouldn't even need to be had. Then, there are the people who go through the drive thru for symptomatic COVID testing (and to specify, this is not a rapid test...they will find out in a few days) and then come into the store to do shopping and pick up a prescription at the counter. And no, this is not something that has only happened a few times.
Also, one of my techs got COVID at the beginning of this whole thing. We were all wearing masks at work. We work in, essentially, a room the size of master bedroom together for ~12 hours a day. She was the only one who got it.
I am, by no means, trying to say that all unvaccinated people wouldn't mask up. I know there are MANY who would. I'm just sharing my observations from working in a public space and providing healthcare for the past year and a half.