I'm starting to get worried now that you put it that way. Mario Kart 8 didn't even have an on-screen map (except for the Wii U GamePad) before an update. Seems Nintendo is getting a little lazy and not giving its games that 100% polish. Prior Mario Kart games that I've played always had an on-screen map, e.g. Double Dash!!.
They were probably hoping that people would be satisfied with the GamePad but since fans complained they updated it, thankfully!
Captain Toad: Treasure Tracker could work perfectly with the Wii U Pro Controller if they were to make it compatible and when to blow on the GamePad the solution for the WUPC would be pressing the L + R or a similar combination.