Ask HN: Is 1080px Wide Too Small for a Web Browser?

I use a Mac, and an app called Divvy to manage window layouts. The main way I use my laptop screen is in a 4 column layout where the left-most column is a utility of some sort, and the right 3 columns are my main content. Sometimes this is a terminal and text editor respectively, but often it is my Twitter client and Chrome.

This means that my web browser is constantly 1081px wide, and this is my question: is it now unreasonable for me to expect the web to 'work' at that size?

With that width, I'm under the threshold at which Bootstrap starts scaling down content, so most Bootstrap sites display incorrectly, often so badly that I can't view them at all. But also many other 'responsive' sites just fail to display in a useful way at all.

I remember the days of designing the web for 1024x768 as it was the lowest reasonable common denominator I can remember (thankfully I missed the 800x600 days!). Has the web grown up to 1280 as a standard width now, and if so, is that a good idea? The main reason I don't use my browser at full width is that it wastes so much space on so many sites.

What do designers typically target now? And do you think the rise of frameworks that do responsiveness automatically is bad for design because people don't know how to use them correctly?