Manufactures like it because they get to put a bigger number (measured by inches diagonally) on widescreen monitors compared to a 4:3 monitor with the same area

Manufactures like it because they get to put a bigger number (measured by inches diagonally) on widescreen monitors compared to a 4:3 monitor with the same area (measured by width*height). But we're doing the disservice to ourselves when we buy it, so your point still stands.