An alternative perspective - for people that travel a lot, that 300 grams (.6 pounds) - is a deal breaker. Also, you really have to be a power user to need more than a MacBook Air can give you in terms of performance - my 2010 4GB 256 GB SSD MBair is plenty fast for me, and I'm probably pushing it harder than 95% of "road warriors" do.
It may be the case that people value the mobility so much that Apple isn't dropping the price on the MacBook Air. (Or, alternatively, people are no longer buying the heavier MacBook Pro, so they've dropped it's price.)