And yes, many/most PC ports are of very low quality. Gone are the days of PC-first Triple-A games with forgotten features like Quick-save/load, LAN-multiplayer, Map-editor, official Mod-support. These days, these ports feel like they started porting two months before release, done by two coders. All these console-ish things like messages "don't turn off your system" (yah-right), press a key to start (yup), save-points (wtf), always-on single player (...)

I assume title screens are just that: title screens, and the developers want to show off. Maybe it's a legacy of arcade machines, though.

Instead of a title screen, PC games used to go to the main menu directly.

Even today, some console games like GTA V don't have a title screen, but many smaller games feature a useless title screen.

What is the rationale behind such a requirement?

>if the game takes too long to load before the menu appears, pressing A will circumvent that requirement.

Does this mean those screens/videos that get displayed after the game starts and before the menu appears are required by Microsoft to be skippable?

If that's the case then it's good UX design in my opinion. I think those things are an unacceptable waste of player's time; I hate them so much I rename the files in the game's directory so it will fail to show them.