It's still an up-port of the Wii U version, don't fool yourself.
...Which is releasing at the same time and is also $60?
Breath of the Wild is a console game. It's being released on two consoles. Both are retailing for $60 because it's a full fledged AAA console game. Nintendo isn't wringing an extra $20 out of anything for the Switch by wording their marketing as a console you can take on the go.
If BotW was $80 on Switch, you would have a point. But it's not. It's $60. Just like it is on the Wii U. Because it's a full console game, not a smaller handheld game.
There will be smaller handheld games for Switch, and some of them will even be made by the handheld Zelda team. If Nintendo tries to price
those at $60, you send me a PM and I'll concede the point, 'cause that would be BS. As it stands your point makes no sense at all, all their announced $60 games are clearly console experiences, and their announced smaller handheld-esque experience, SnipperClips, is priced at $20.
Or do you really think that BotW Switch should be $40? And SnipperClips should be free?
Edit: Also the term for a game releasing simultaneously across two generations of hardware is called Cross-Gen, not an up-port, and Nintendo is not even close to the first company to do it.