I've never been a fan of character weapon skill being tied to the bullet not hitting where the player is aiming in first person RPGs and immersive sims. Think something like Fallout 3, where a shot with a sniper rifle can be perfectly lined up, but the bullet might veer off randomly.
I do understand and appreciate character weapon skills being tied to certain weapons being more viable, but there are many other ways to impliment it that don't feel as arbitrary. Tying character skill to greater reticle swap, longer time to aim down sights, longer reload times, more likely to jam or jams taking longer to clear. It accomplishes the same goal of rewarding putting points into the skill and making players feel like they are progressing, but without creating the instant frustration of missing a clearly lined up shot.
On that note, actively degrading weapons are not something I think has ever been a good idea. It's neither fun, nor is the rate of degradation ever realistic. If the goal is to make player cautious, then limiting ammunition and the availability of good weapons is a much better idea. I have no problem with weapons in different conditions existing in a game, for example: Pristine rifle, good rifle, rusty rifle, etc. That's fine, but a good rifle should never degrade into a rusty rifle in the hands of the player.
Areas of open worlds dynamically level scaling to match players is another gripe I have. Once a player notices it, it takes away the feeling of progress from leveling up. In some cases, smarter players in games have found certain areas easier to beat with low level characters. It creates a bad kind of meta-game. I much prefer worlds where every area is built with a certain player level in mind. Honestly, overleveling in RPGs and going to wreck starting bandit camps is a joy that shouldn't be taken away.