Why would they need WiiU pro controller support?

I don't think they need either.

The Switch pro controller is closer in layout to the gamecube than it is wiiu pro controller and it has every feature plus some to that of the wiiu pro controller. It really seems like rumor with no actual customer value and thus not going to happen.

While this would be nice this is almost downright wishlist - y and browsing through their previous posts and claims shows their sources are not really reliable, getting very very few things right.

Yea like I mentioned in an old VGC article it would be a kind gesture to the loyal Nintendo fans that had a Wii U to allow Wii U Pro Controller support for the Switch. It is almost like a middle finger to not allow it especially with how they let you use CC/P and Wiimotes+nuchuck with some Wii U games.  Not having to buy controller every gen is a god send but you know them pockets need filling.

To give a pat on the back of the loyal Nintendo fans... You think I'm giddy to drop 80 dollars on a new controller.  Shit remember when controllers were 20-30 dollars.   I believe the Wavebirds were retailing at 35 (I still have 4 of them considering I had terrible luck with wired GC controllers).  Then all of a sudden controllers cost a shitload after PS2/GC/Xbox generation.

One thing I really liked about the Wii U was the controller BC so I hope Nintendo adds support for both the U pad and the pro controllers as well as Wii and GC controllers. It always sucks when a new system arrives and you can't use the controllers you already own despite them having all of the required buttons.

YES, PLEASE!

Don't want to invest 150-210 dollars in 3 Switch Pro Controllers, despite of the fact that the controller itself is fantastic.

It has 3. 

That one on the back is USB 3.0

Why not support the Wii u gamepad and wiimote as Well then? I mean it would be pretty easy for them right?

So the idea is to not have to buy a new pro-controller, though you lose all rumble, nfc functionality, and arguably better configuration and build quality. Guess that's not a bad trade-off considering it also goes from 40hrs battery to 80hrs of battery life. I just didn't see how this related to smash bros, but I didn't think of just using it for switch in general. Though I do think the Switch controller is a big improvement over WiiU version.

To clarify, I wasn't arguing that more support shouldn't be provided, just didn't see value from a SSB perspective considernig the layout and functionality of the existing pro-controller.

It'd be extra nice if the Wii U adapter one worked as well. It would save me some time and money...and it'd be nice to not need a 2nd one...