1920x1080 screens have 10% less vertical space than the older 1600x1200 screens. When writing code, it would be nice to have the extra 120 pixels available to see more of the file without scrolling. When reading PDFs or ebooks I'd like to see a single large page instead of two small pages right next to each other. Same with webpages - 99.9% of websites are hard coded to be <1000 pixels wide. It's pretty rare I need to see two websites side by side, but I have to do extra vertical scrolling a million times a day.
I've never seen the benefit of tiling a bunch of windows, either. I can only concentrate on one window at a time, so, IMO, showing a million windows just adds a bunch of distraction.
Widescreen is nice for watching movies, but terrible for everything I spend time doing on the computer.