How is Windows 8 missing so many major apps?

Hey,

I just bought a new W8 laptop, and I really love it. However, I'm shocked to see how many expected apps do not exist in the Store.

No Facebook? No Google Maps, YouTube, Keep, etc? That's just what I've noticed so far, I'm sure there are more that will shock me, haha.

It's not like this is Blackberry, it's WINDOWS! How are developers not interested?