I've heard the excuse that they have to buy LCDs from companies whose primary customers are TV manufacturers. The end result is the same of course, but the laptop manufacturers would have to cut their LCDs in shapes that would result in waste to produce machines with reasonable aspect ratios. (Of course what this means practically is that I'm just not going to buy a new computer, so whatever.)

Everybody says this, but it doesn't make any sense. They don't sell 1080p TVs at small screen sizes. A 15" or 17" 1080p panel is not getting sold to a TV manufacturer.

This. And nothing else.

Why oh why do we measure screen size diagonally and not area or something that actually makes sense.