Under-seasoned food tastes bland but well seasoned food never tastes salty. Without "seasoning" your mechanics will feel bland and players will be underwhelmed. But over-do it and the players will be hesitant about your "salty" mechanics.
Adding what game devs call "juice" to your game is a bit like seasoning food. A gorgeous dish made a talented chef will be bland and tasteless if he has neglected to add salt, but be salty and off-putting if he added too much.
It must be proportional to the mechanic and the frequency of use. If you have a machine gun but with every round there's big screen shake, interstitial black frames, knockback, etc, etc the player will quickly tire of it. But it might be right for a bolt action hunting rifle.
But have some friends over and everyone wants to play a game then learning the game and playing multiple rounds is impossible.
So you just play shallow games or stuff "everybody knows."
So the best games get to sit in the cupboard unless you have a dedicated group.
An issue I've had with board games is that games with good depth should be lengthy enough to explore that depth and will take many round to understand and make use of the full range of that complexity.
I believe in a "less is more" and "show don't tell" approach to writing games. Regardless of whether it's dialogue, narration, hints or even in-game documents. If a film or series were written like most modern games it would be like a Neil Breen screenplay.
We all love diegetic UI. But I think forcing it where it doesn't work well can be more immersion breaking than a simple HUD element that you get used to and forget.