Someone at my work did something like that, got infected, had to take them out... Now he looks like he has 2 bellybuttons on his face... Yuck.

I really, really, really want to try to land a peanut in that from across a crowded room.

I never said I like it, which I really don't. I just think it works. If they're lazy or untalented, it doesn't really matter if they're selling well. I personally consider anime art, but it's also a merchandise, we shouldn't forget that.

"to claim that one minor thing ruins all of anime faces"

I have to agree with JayOhAych. And that's the odd thing I've learned in my years of drawing; less is more. Sometimes leaving these gaps or the barest hint of a line in particular areas will give your brain a framework around which details are filled-in automatically (the so-called gestalt principle). You are…

It's a shitty artstyle that originated from cutting corners in animation, so there's pretty much lots of things wrong with it.

It's meant to show where the lips purse together. It is a stylistic choice that operates on the gestalt principle of closure.

Hey, look on the bright side of things! It should be that much easier for his dentist to get at all those problems.

The reaction can be controlled (crying, debatable), the emotion itself cannot.

I don't think it was said anywhere that it ruins all anime, just that it looks tacky, and poor execution can indeed ruin an experience (we know that from games a lot, like graphical issues during cutscenes and such). So although it's not some world ender, it looks like crap.