The architecture is practically irrelevant when writing code that isn't assembly. It's all down to the same C/++ code as anywhere else, combined with Nintendo's libraries (which abstract the process) and APIs like OpenGL allow GPU control without thinking about the target platform at all.
Assembly is practically not found anymore in games unless you're on your knees for performance. Most games use a cross platform engine like Unreal or Unity anyway that does all the platform specific work for them. It's simply a matter of power, and the Wii U was behind without a doubt, but it's not far off the Switch which is still getting support. No reason the Wii U couldn't have been supported by the same token a few years before.
Regarding the examples, the Saturn was a time when assembly code was still definitely there in games and it was a nightmare to manipulate 8 processors at a machine level, and the PS3 didn't have much "untapped power" - it was very fast in specific, raw compute scenarios, but the feasibility of those numbers dropped dramatically when you consider that the coprocessors could not effectively "branch" code (no proper branch instructions), had to be babysat by the single PPC core and was further tied up with a long, in-order pipeline and small caches on the SPEs which made them only useful for specific, uncomplicated code.
Returning to the point, the Wii U's architecture was not an issue like you might expect and if anything it had many features that allowed it to punch above its weight (its pocket of eDRAM was obscenely fast, like a supercharged 360's - it may be as high as 563GB/s) if you wanted to tap its "architecture". Let's not forget that the GPU was very good at assisting the CPU to further negate the PowerPC problems. (The reason many third party devs didn't cop this at launch was due to poor documentation and time constraints, and then it was too late for most)
The point being that a lot of pre-PS3 comparisons are negated by the fact that advances and expanses in games as a whole have invalidated many of the arguments made (storage space and transfer speed are practically non issues now, and because of modern engines you can design a game and the engine does the platform specific work). Even in the PS2 era you had games (particularly in Japan) where engines were built from scratch for a game but that just never happens now.
The marketing was definitely an issue, with some advertising not making it clear that it was a separate console and not just an accessory to the Wii - accentuated by the fact that using Wii remotes and software was a big selling point. I don't know if it was the entire problem but it was a factor.
My point about the Wii, by the way, is that it's unfair to compare the two virtual consoles by saying the Wii U took two or three years to get going when it took the Wii two years to launch the service as well.
I was not aware of those issues surrounding metacritic. I simply believed that it was better than linking single review sites. In any case the general consensus between user and critics is the same in most of the aforementioned games.
The thing about Mario 3D World is that I don't feel it was the second coming of 64, but when people talk about it, it's never negative. Of my small sample of people who've talked about the game they've all quite enjoyed it. It didn't reinvent the wheel but did a lot of things right.
I will happily take you up on the offer to put other stuff I write on the portal, though!
I mean, look -- if I'm being transparent, I'm not a fan of Captain Toad, Star Fox Guard or Splatoon. I enjoyed Splatoon for a while but it's just not really my thing if I was asked to play now. Sure, the world doesn't operate on effort, but to say Nintendo only produced CPR games for the Wii U is unfair because they certainly gambled with games like those - and Splatoon, at the very least, was a comparatively huge commercial success. (I also didn't mean to imply that Splatoon pioneered zone conquest gameplay! I've played Battlefield since BF2: MC on PS2/Xbox and I've enjoyed many a Battlefield since.)
I also believe BOTW is overrated as it has some fundamental issues (open world with either filler quests like locating based on pictures or emptiness, zero difficulty progression etc.) but that sounds like a separate discussion! In any case I agree. I didn't enjoy Xenoblade on Wii that much, because while I loved the environments and the characters were fine I just really couldn't gel with the combat compared to, say, The Last Story.
I think the Wii U offers a reasonable snapshot of its time, for better or worse. Games like Mario Party are dragged kicking and screaming into the current day with little interesting derivation on the original formula (with 10's Bowser mode being flat out bad) but Splatoon shows that Nintendo were still doing their best to try new things in at least some ways.
Side notes: I enjoy Mario Kart as a casual game with a few rounds of split screen but I haven't been knee deep in the series for years. I miss Jak X and other kart games
I also passionately believe that we need new racers of the same vein, because now you will find hundreds of children all playing Mario Kart Wii
competitively (ie. the one way it was not meant to be played) to toxic degrees, with everyone choosing Funky Kong or Daisy because of slight internal stats that give you an edge. That's no fun. They're doing this because there are just no other kart racers around anymore.
Ultimately there's no way I'm going to change your opinions on any of these games but all I wanted to do by drawing your attention was to at least present an argument that there are a reasonable amount of games that some people may enjoy on Wii U.
I enjoy a few games better on my Wii U thanks to the gamepad functionality; I bought Splinter Cell Blacklist on PC, then on Wii U a few days later and ended up completing the Wii U version sooner, despite the benefits of PC (Maxed at 1080p, running @ 60FPS, mouse...) because the gamepad offered a different gameplay experience that I could simply get behind. It's not for everyone, but I'm not the only one to hold this opinion.
(Also, a little bit of your post sounded adversarial, and I wanted to make it clear that I'm only here to have a discussion, not defend anything to the bitter end or change anyone's mind)