Firstly, why can't people learn that listing the releasing games in the OP hardly proves anything?
But let's look at this a different way. Quarterly sales, and market share.
Q4 06 - 1.13M - 62% Market share
Q1 07: - 1.07M - 70%
Q2 07: 0.96M - 82%
Q3 07: 0.76M - 73%
Q4 07: 1.24M - 66%
Q1 08: 1.14M - 73%
Q2 08: 0.69M - 73%
Q3 08: 0.5M - 65%
Q4 08: 0.83M - 62%
So far into Q1 09: 0.34M - 49%
You're telling me that's not a huge drop marketshare wise? It's dropped from having 70-75% to being around 50%.
So far into Q1, Wii is at 48% in Others. Japan may very well end up being the Wii's weakest area (marketshare wise).
In the OP, you're talking Market Share, so that's what I did. Looking at market share, people aren't overreacting at all.