Personally, I like to see a reasonable amount of information displayed on a HUD and have it take up as much space as necessary to get the point across, but no more than that. In 2016 I prefer the HUD to be scalable, to support all common aspect ratios including 16:10 (some games like Witcher 3 do not scale the HUD to 16:10 when using 16:10 and that's one annoying glitch), and if it makes sense or would be useful, to allow turning on/off individual HUD elements and possibly allowing them to be placed by the user where they want them.

Additionally, even though I would most likely not use it myself, all games that have a HUD should have a way to disable it for screenshots and for players who really like to have a HUD-free experience. They may be few in number, but it is literally one line in a config file, and probably one to ten lines in a game's source code to just not display something, so pretty low effort to do.

Personally, I think that screenshots should include the HUD, as it communicates useful information about the game state, like if the character is almost dead when the screenshot takes place, or if (due to a bug) the player's health is well above its maximum or negative, for example.

People like to take screenshots for artistic purposes and purposefully hide the HUD to see the actual background etc. like a photograph.

I am an idiot. https://static1.artfire.com/uploads/product/8/698/63698/6963698/6963698/large/kincardine_ontario_souvenir_collector_spoon_collectible_ship_wheel_vtg_11c3faab.jpg
Interesting, I take screenshots because of the game world and don't want a HUD on them.