A GUI by itself will do little for adoption.
Except in the case of Monero - where it has taken so long that it's the equivalent of Duke Nukem Forever, and people that had no interest in the coin at all will just be amazed if it actually comes out and download it just to see what the hell it is.
I get that you're (probably) joking, but it's still worth noting that DNF was a
product (and a much hyped one at that) designed for the end user, whereas cryptocurrencies are protocols ultimately intended for integration into other systems and services.