While the test is comforting (typical nintendo), I have to agree with you. They should have tried to play with it to see if it works properly.

Also, a "sitting" test with someone of 80 or 90 Kg would have been nice.

Am I the only person who doesn't think it feels cheap? Everyone says it does but I feel the quality is actually quite good. The console felt sturdy, and less cheap than the 360 and PS3. The controller felt more well built than a DS3 and the 360 controller too.

as expected of nintendo products

Some are durable, my Gameboy still works with just some faulty lcd lines. Meanwhile this gen I have had problems with both my DS's: a DSLite which had a broken hinge that I replaced the whole housing myself and a DSi mysteriously stopped working - got no idea what happened to it. Plus a dusty Wii drive that doesn't let me play Smash.

Every cycle has its bad apples. My Launch 360 and Wii still work fine. Same with our launch model PS3 we acquired recently.  My Wii reads games fine. My DSi I sold my brother still works, my little brothers DS lite still works. A DS phat my friend gave me that she accidentally ran over with her car still works aside from needing a new battery. (No screen damage on it either just casing) and my 3ds is flawless so far (knock on wood)  Then again I try to treat my hardware wonderfully.  My GBA:SP works wonderful, my GBA color works like a charm (and it took some abuse) my GBA broke, but this was after letting my little brother borrow it a while back. You must of gotten unlucky.  I've only had Sony consoles give me trouble.  And those were Disc read issues thanks to their horrid disc drives on the PS1/PS2 and ultimately the PS3 shared the same issues.  Obviously 360s had an extremely high failure chance out the gate so I happened to get lucky and kept my 360 cool enough. Every console run has its lemons.  Though that being said I would trust dropping my GBA:SP on a hard surface, but not my 3ds if that gives you any example of the quality reduction. 

Just checked my N64 and the reset button was stuck for a sec but went down after a good push and now feels "normal".  I assume it still works but I don't have it hooked up.  I had a major problem with the c stick messing up and b button sticking on GCN wired controllers though.  I kept sending them back and they kept messing up after a week or so of use.  I eventually just gave up and bought all Wavebirds since I never experienced the problem with them.  Some reason the wired GCN controllers were shit to me.
 

Of course and passing from a single body design of the Gameboys to the DS clamshell has brought extra fragility. Any ways, I don't think much of it as it also has its perks, i.e. if the Wii problem worsens it gives me the perfect excuse to get a Wii U sooner than later.

Why don't you try the Wii's lens cleaner?

I had problems with my launch Wii to read Xenoblade, but after 1 use I've able to play it without problems.

Good point.  My first white DS Lite was a victim of the notorious faulty hinge, which just had a visible crack at first but eventually completely broke.  The system still worked, though.

Don't bring a cheap solution into the mix! Now I won't be getting a Wii U...