It's simple, mainstream, American movie studios aren't in business to break even/make a small profit on the back-end of a movie. If a flick is successful domestically at the box office, then overseas sales and after-market sales are icing on the cake.
Of course they love that kind of money.
But if a movie fails domestically, then the chances of it turning a significant profit from overseas sales/Blu-Ray DVD's is very low. At best they'll be lucky to break even (if that).
Film budgets don't reflect money the studios have to throw down for marketing, promotion, etc. And the box office numbers don't reflect the actual money the movie studio takes in either i.e. they only get a portion, not the entire sum. And those dollars are gross, not net too.
So if a movie is already significantly in the hole that 20-30 million you're talking about with DVD sales isn't going to be profit. It's just more bandages for the wound.
sure for some movies it really doesn't matter, but lots of them make crazy sales!!! 
I felt the same thing. It even translated to the NECA Figures. I was so excited they were doing the Jaegers, then I saw them, and the small size just made me lose interest a little. I know they can't be built to scale, but 7" is too small.
