The issue is that Rogers has, for some time, been claiming that these are straight ports. With cross-play, even.
Nothing has ever worked this way. My mind is honestly blown that you think it should work this way. You do not own a game released for one console just because you bought it at one point on a different console. You own the WiiU version of Mario Maker. That is the game you paid for, not every re-release of Mario Maker that will ever happen in the conceivable future.
It ended up working that way for a lot of games I bought on Xbox one and nearly every game I've ever bought on steam and iOS. With Xbox one obviously that wasn't the case at launch and was a value add. But It's an expectation of digital purchases that is completely fair assuming the game hasn't been significantly reworked or enhanced. If they release splatoon and it's a completely new experience then cool.