Besides, I much prefer running a somewhat low-res desktop with high-res programs opening on their own screen.
Scalable fonts. There's just no reason to subject your eyes to low resolution any more.
Left Amiga+M is instantaneous and depends only on the monitor resyncing. On Windows, try Alt+Tabbing to PowerPoint after you've been working in another program for a while and see how long it takes. Try Alt+Tabbing back from a game to look at another window - if it even lets you.
Maybe on Windows, but these days on my Linux laptop, switching between apps is instantaneous, even with a relatively anaemic integrated Intel GPU.
Oh, on a related matter, my usual old chestnut: the ability to have the active window not be the frontmost one - how the Windows/Mac/Linux world hasn't gotten to this one yet is mind-boggling.
They have. A large number of Linux windows managers have been able to support this since the mid 90's (inclduding "AmiWM" which tries to make X Windows look like AmigaOS), it's just not popular with users and so pretty much none ship with it enabled by default, and it's a "dying" option.