Why? Because "at this point", the MILC adoption rate is still tiny. I was out shooting at a street fair today, and I saw at least a dozen DSLR users, but I was the only MILC user (using an Oly E-PM1). Look at Amazon's best selling cameras list. Last time I checked, there wasn't a single MILC camera on it.
That's only in the US, and US does not represent the world.
In Japan, the mirrorless market share is over 45%, and it is poised to overtake the traditional DSLRs very soon. And Japan is one of the most valued market for Japanese camera manufacturers as it is their home market. In the month of June, 14 out of the top 30 cameras in BCNRanking monthly sales chart in Japan are mirrorless cameras. The same high penetration rate is seen in other Asian countries such as Korea, Taiwan and Hong Kong.
In UK, it's about 25%. In US, it is between 5-10% (and it just shows that the Amazon list really is not representative at all even for the US market).
Overall globally, the mirrorless market share was 23% between Jan-May 2012.
So I would not call the adoption rate tiny by any stretch of imagination.