How about...because it's brand new? This things have been in the stores for all of a couple of days. And this is Japan, not America--people do not (generally) go into stores and chew on display units or attack them with chainsaws.
You people just don't get it, do you? I know you want to love the DS Lite and have it love you. Believe me, I do, too. But the buttons on this thing suck in a way that buttons have never sucked on a Nintendo controller or handheld.
The DS Lite's buttons are NOT like the buttons on the Micro. The buttons on the Micro are awesome. They aren't clicky, and yet they're highly responsive. It feels good when you press them.
If you'd like a good simulation of the DS Lite's buttons, take out a soft dishrag and hold it in your hands. Now press it with your thumbs. Does that feel nice over on the left? Do you know which way your character should be moving? How bout on the right? Think your character should be jumping about now? Don't know? Well, try pushing it a little more maybe.
The buttons are not just "soft" as in "easy to press." They're loose. One of the problems is that they are oddly tall but narrow. This means that they don't just go straight up and down when you press them; they kind of smoosh to the side a bit. The D-pad is especially bad that way. It mooshes all over the place, so I was never really sure when I was pressing it hard enough / in the right direction to be doing what I wanted to do. I'm sure you'll get used to it after awhile, but that doesn't excuse the fact that it's a piss-poor design. That would be like excusing the original GBA because IF I STAND NEAR THE SUN OR ANOTHER VERY LARGE STAR I CAN SEE THE SCREEN JUST FINE SO SHUT UP THE GBA IS AWESOME AND PERFECT!!!!!!!
Oh, and the start and select buttons are totally different. They are extremely clicky and hard to press. You have to put far more pressure on them than the other buttons and push them down pretty far, then they go "click."