NW had there own issue a few months ago during the runway 16L/34R closure at SEA. There were some instances where they had to offload passengers/baggage in order to get the 753 off the ground.

As for the 757 being 'over-engineered', I would point out that it was designed to most efficient and versatile on the higher end of the medium haul spectrum. Originally conceived as a kind 727-ER, it eventually morphed into a completely different type, essentially a 767 on a diet. The 737ER and 739ER come pretty close to filling the gap in the product line left by the discontinuation of the 757, however, I suspect whatever next generation narrow body type eventually replaces the 737 will look a lot like a slimmed down 787 with payload/range specs very similiar to the 757.