Yeah, pretty much. Also, standard video aspect ratios like 1280x720 fit the full width of the monitor with space above and below for toolbars and video player UI, which is... basically impossible to convey how frustrating it is to watch video on a widescreen monitor when you've tried a proper one for comparison. Any kind of fullscreen (ie maximized window) games or multimedia is similar.

I understand the bit about a video players, but you're not going to want to play a game in anything except exclusive fullscreen due to the massive input latency incurred when using windowed or borderless windowed.

Depends on the games you're playing, honestly. That "massive" latency is about 30ms from what I can find, which you're not really going to notice when playing a game like civilization or hearthstone.