Well Jo, in their defense, I never heard you complain about the Inquisitors in Rebels when their "Grievous-spin" doublesabers were the hot new thing :p
I'm sure there were people like you guys in 77 who looked at SW and said "Lightsabers? That's just dumb." xD Haters gonna hate.
Actually, considering that this is basically a sith version of the Jedi Temple Guard saber... could Rey be disguised as some sort of Sith temple guard?
The flipsaber is juste a practical way of carrying a double bladed lightsaber. Pong Krell had them in The Clone Wars, and so did the Temple Guards in Rebels. And it looks cool, which is the main point of any lightsaber.