I understand the difference people expect from GUI vs CLI, I just don’t think it really makes sense to be ok to pay for one but not the other, and I see it as a missed opportunity for tool creators.
Edit: Regarding Linux users as the main target, I don’t know if that’s true. I had mostly macOS in mind (I know I explicitly mentioned APT in my initial comment, that’s just what I had in mind at that moment), mac users seem to be ready to pay good money for their tools, there is a healthy market for GUIs. Something equivalent to homebrew cask but with an economics component may have its users if the tools being sold are considered valuable enough.