Could be worse. You could have the Moto Gamepad Mod, which only supports one phone. (Well, three if you want to count all three generations of the Moto Z series phones.)
@dual_sport_dork Should still work with some custom 3D printed adapter, shouldn't it? But it definitely looks harder to create the adapter than a case.
Negative, unless your phone has the connector pads on the back for Moto Mods, which only the Z series has. The controller has no other way to connect to a phone.