I'm not saying that the wiiu will steal switch sales, but in a way or another people will know about the wiiu, what i'm saying is:
-think of people looking at the ad with just Zelda that's also on the wiiu, do you think they'll say: "Switch has lots of games!" ? I don't think so.
-wiiu is a bad legacy, it makes people more cautious, make people wonder if Switch will have third party support.
Basically the wiiu won't steal anything but it will have a bad effect on switch sales.
Again, the Wii U wouldn't even be a consideration for the general public. Just because someone on GAF may look at the Wii U's third party support and be hesitant about the Switch's doesn't mean someone a few days after the Superbowl looking to get a Zelda machine is as well. There's also the fact that, for someone researching the Switch, they'd have to actively go out of their way to research the bad points of the Wii U to even "know" about them in the first place. It's not like Nintendo's websites or retailers actively advertise the fact that Wii U barely had any third party support.
There's also a bit of a paradox in your argument. People will see Zelda being on Wii U, a literally dead console, as being an indicator of the Switch not having many games yet somehow they will also care about third party multiplats as well.
The bed scene is totally futile, a waste of time that imo won't be even liked by parents, the real important part of the ad is passing seamlessly from handheld to home console mode, once you have shown that and zelda you can spend the rest of the time showing more games to give the idea that lots of games are coming, because the point of a 30 seconds trailer isn't to make people understand what a game or console is, people won't even understand Switch or Zelda despite all the time they got, the point is to raise the interest of people, the more you show the better.
The bed scene isn't futile, it's establishing a narrative which is entirely what commercials are supposed to do. Lets look at one of, if not the most well-known adverts, well-regarded trailers of all time. most well-known adverts of all time. By your logic it would have been more effective if it only consisted of the last 5 or so seconds or if Apple replaced literally all of the other "futile" stuff with quick-fire shots of Mac software. If you want a more game-focused example then look no further than this
Again you've come to a paradox. You say that Nintendo has to pack a 30 second ad with every game they can to "let people know lots of games are coming out" yet above you've stated that customers will research the Switch to, somehow, also learn everything about the Wii U. Would those same customers not also see the other advertised games during their research? How would a consumer who learns about the lack of Wii U third party support not also know about the other games coming to the Switch?