You either:
A. Having a serious reading comprehension problem or
B. Did not read a single thing in my post or
C. All of the above
You are going to sell more units of something if it is readily available VS something that isn't. Saying the Wii U sold more units than the 360 / PS3 at launch is an unfair comparison. 360 / PS3 were sold out everywhere for at least 5-6 months after their launch and reflected negatively in the "launch sales" because people couldn't find them to buy. The Wii U had massive OVERSTOCKING and still sold far less than was expected.
If you don't follow any of that, then please get ask your mom or dad to explain it to you.
If wii u was overstocked then why was there a shortage before xmas? Do you have a source for this supposed "Massive overstocking" of the Wii U?
As far as I'm aware the original Wii had a shortage problem at launch too (especially considering it's the fastest selling console ever) yet it's sales figures at launch are better then 360 and PS3.