I have a 27" monitor, and 90% of the time, it shows a single maximized app, with the browser second in the Alt+Tab stack (so you can switch back and forth just pressing it once).
For the browser, it does (wasted horizontal space), but you can also rephrase it as "less distraction".
Most productivity apps, however, have their own way to subdivide space within the app efficiently. E.g. in the IDE, there are various panes and tool windows. Put a file browser on one side, a documentation browser on the other, and a terminal pane on the bottom, and it actually starts feeling kinda crowded.
