Why are people so against OPTIONS in games?
Splatoon makes heavy use of motion controls, and despite motion controls having an advantage over dual analog, the game still supports dual analog as an OPTION. Off TV play with an onscreen map should be an option, even if it theoretically puts you at a disadvantage. At least give the player the choice to do so.
Having an onscreen map also would've made Splatoon a better spectator game. The lack of a map makes streams of the game boring to watch, and (laugh if you want) limits its "eSports" potential.
Xenoblade X, for example, is much less convenient when using off TV play because of how the map is designed. They did not redesign that way the map works for off TV play, and it's less than ideal...but they still give you the option, and I greatly appreciated it, having played the majority of the game on just the GamePad screen.
I think having a barebones Off TV feature is better than none at all. Yes, people would likely bitch and complain about it, but many would still appreciate the option.