I didn't really understand your reasoning, but I also doubt it will have a touchscreen. Not only because they did not show it all in the video, but because the tablet is docked during home use. The Wii U was able to have a touchscreen because it was designed for you to always have the gamepad in hand. Because the Switch is intended to be docked, it would not make sense to require a touchscreen at any point, because this would force the user into taking the system out of the dock and losing their feed to the TV. That doesn't make any sense for a home console.
If there is any sort of touchscreen, it absolutely can never be a requirement in any game. That would make the game incompatible for docked use. And given that... There really is no reason to add a touchscreen at all if it's not intended to be utilized. They already tried that with the Wii U, which was designed to be played with two screens, and those features were grossly underutilized.
If there is any sort of touchscreen, it absolutely can never be a requirement in any game. That would make the game incompatible for docked use. And given that... There really is no reason to add a touchscreen at all if it's not intended to be utilized. They already tried that with the Wii U, which was designed to be played with two screens, and those features were grossly underutilized.