The Switch could be the most amazing console ever, without the steady stream of awesome games it is getting it wouldn't be selling half as much as it is.

I have to disagree on this. There a lot of several factors that can impact console sales. 

As for WiiU:

1) It is the worst Nintendo console in terms of games lineup. It’s launch lineup of games was bad as well. They’ve had zombiu, Nintendo land and probably some mario game. I don’t remember exactly. In terms of third as was already mentioned they’ve had old 360/PS3 games. Also this games were the so-called worst versions. If i’m not mistaken black ops 2 was 30 FPS game on wiiu. Not surprised almost nobody bought it. To be honest if it wasn’t for super smash, splatoon and Mario Kart I think wiiu wouldn’t have reached even 10 million lifetime. 

2) The name. Nothing to say here. A lot of consumers thought it was a wii addon. 

3) The point that I’m surprised nobody mentioned here. But back in 2012 wiiu had a massive problem with day 1 patch. It was required to download day 1 patch in order to use a console. And for some reason the update process took almost 1,5 hours and if for some reason the power went off in your house during this process, the console would brick. There was a lot of negative PR created by this. So I think that is also a reason why wiiu sold that bad

As for Xbox One:

1) Always online and DRM stuff. While I understand why Microsoft wanted to try this. They probably want to get rid of physical distribution because it costs money to print discs. Also this worked well with steam on pc. Though it turned out that console gamers aren’t big fans of digital distribution like pc gamers so it didn’t work out. 

2) Focus on TV and entertainment. That’s simple. It was really stupid from MS to go after this crowd with 500$ price tag. It is just too expensive for them. Though if Xbox One would have cost 300$ or less I think they’ve really had a chance to sell it to this casual crowd as a media entertainment system and even probably reach the desired 200 million sales. 

3) Architecture. ESRAM was a big mistake. Xbox One x shows that MS themselves understand this. Also this gen is the first time Sony were able to make a better console architecture-wise. 

4) The main problem why I think Xbox One sells bad everywhere except US and UK. It was only released in 20 countries or so in 2013. In the rest of the world even in a lot of European countries it released in September 2014. This gave PS4 almost a 1-year head start. To be honest everything about Xbox One release makes me think that MS planned it to release in 2014 but they rushed it to the market when they’ve found out that Sony will release PS4 in 2013. MS just didn’t want to give Sony one year advantage so bad. 

As for switch and PS4. These consoles didn’t have such big problems so no surprise they sell that good. 

Sure 3DS had a bunch of killer apps just like DS, but wasnt just that that made the console sell well. There were a inherenty quality in it.

Lineup is important.
Power is important.
Marketing is important.

Being strong in one area can make up for weakness in other areas, though.

Yep, SNES was the best console ever imho, so that's what the Switch is aiming to surpass. And with Nintendo focusing all their efforts in one piece of hardware... I can only dream on what the catalogue is going to be.

For example, just imagine if Switch games were great but the hardware itself was a mess. Problems with overheating, battery life, unreliable hardware, super cheap build quality and etc. It could have all the killer apps from Nintendo it would still be held back in sales.

About 3DS, games are important, but, it still had to get a massive discount before the first anniversary because the consumers felt the hardware was too expensive for 250 USD.

Switch:
-Good and apeling hardware for mass market.
-Strong launch and 1st year lineup of games.
-Strong marketing and branding.

I would agree that solid line-up for Nintendo console is extremely important compared to PS and Xbox because Nintendo dont have strong 3rd party support like them.

Power is not important unless you have almost same product, like PS3 and Xbox360 or PS4 and XB1, if you have consoles that so similar than power like on few differences can be important. DS/Wii/3DS and Switch now were/are popular despite they are not powerful consoles.

Bruhh wut? MS 1st party is on life support and even Halo and Gears are on the decline.

It's time people stopped blaming Xbone's sales for what happened in 2013. We're passed it, MS had the chance to turn things around, they didnt, they couldnt.

Consoles need games and thats what MS lacks. XboneS could've turned things around with some new games to go along with it. Hell even with the introduction of the XboneX they still fail to deliver.

*Translated the bolded: Power IS important

Idon't see Wii U in that list. Maybe those Nintendo  consoles made up for the lack of power by being stronger with marketing and games?