Here comes Hukuna with probably a controversial one... possibly but I think some people will agree with me.
UNSKIPPABLE TUTORIALS.
Seriously... it is annoying. I cannot stress enough the skippable part because my lord do I hate them so much. Now, I understnad the point of tutorials, as they are important to some degree, though I am from the school of beleif that the palyer should be allowed to opt out of it if they wish not do to it for a lot of reasons.
These are not ranked in any order, this is just a list.
Reason 1: Some prefer figuring things out on their own. After all a lot of older games did do this to us by dropping us into the game world with little to no information. It was part of the game to learn it's controls and master them. Something was satisfying about finding new commands or things that you could do even if you weren't told by the game about it. An example, there is no tutorial in a game such as Crash Bandicoot 2. THe early levels serve as a sorta of tutorial to hone your skills for later on by being a place with less obstacles etc to kill you and the like. However, many things were hidden in the level some even in plain sight and this made players wonder how to get to things. As A result seeing these things made you want to try and get them or figure out how to do that. THis encouraged you to try and explore the buttons etc. Many other games, especially platformers, used the approach of teaching through Showing or hinting rather than jamming text down one's throat.
Reason Two: Hi game I want to replay and have been playing for years! I already have beaten you to completion many times, I don't need your silly forced tutorial anymore. As such being able to opt out would be a good solution, however you are rarely given this chance etc... Even RPGs tend to force you to as they put all the tutorial text before a choice to repeat that text... this is annoying to me as well. Why not have the characters ask you first if you need that and then go through it if they answer yes?
That is a purely mechanical thing I have gripes with and I will leave this lying here for now. I do have somethings that are storyline related but I will leave those for another time.