I like the idea of the dash button a lot. Even with one click ordering on my phone with the Amazon app that is logged in automatically I still didn't order toilet paper right away when I saw I only had two rolls left this morning. I think if I had had a dash button I would have. And though that sounds silly I think many people operate the same way.
I also want the dash button but have never used Amazon's Subscribe and Save. I think subscription services are advertised as reducing your mental overhead but for me they can increase it as I am worried I will automatically buy something I don't want or forget to cancel the subscription. Plus with things like toilet paper I don't know how often I need to order it, a dash button solves all this.