But, this is more to the point. You allow acrobatics to get around difficult terrain. However, that's not something that's in the game, just in your game. They can't design feats for your game. There's nothing in the description of acrobatics that allows it to avoid difficult terrain. It's not there. Now, it's not a bad extrapolation, I agree. But, again, they have to design feats based on what's actually in the game.
To me, "using skills in combat" would make a fine optional rule for DMs.
Something we discussed frequently while playing 4E was that for a variety of reasons people took more of a board game approach to combat. We concluded that a reason was powers. There were powers/abilities for just about everything. If you let someone do something that was listed as the benefit of a power that they had you were taking away the cool factor of someone else's character.
I see these feats being the same. I describe a section of terrain as being difficult terrain because you have to carefully wend your way through thorn bushes to avoid getting snagged and I let
anyone do it, then the person who took the feat effectively gets no additional benefit. All they get is the extra proficiency bump.
It also feels less creative? More mechanical? More I use my Performance Card? I dunno. But if you have a feat to distract someone with performance, you are just looking at it as another spell. There's no need for RP/dramatic flair or describing the scene.
Can you describe the scene dramatically? Sure. The same way in 4E that I
could have described my fighter's "Come and Get It" as hurling insults at my foe and challenging them. The point is that I never did that. It just became a card in my deck of powers that could be applied under certain circumstances.
For the most part spells, and certain class abilities are always going to have the same kind of feel. The barbarian rarely describes how their blood is boiling, they just rage. But use of skills, particularly in combat? That's always been more "I start singing a song of bravery and courage to the soldiers in order to distract them while Flinx sneaks into the barracks." At that point I can ask for a history check to see if someone can think up the most appropriate song for this regiment (granting advantage if successful) and ask for a performance check.
It feels more organic, more natural then "I have the perform feat so I distract the guards" and "I have the history feat so I assist".
Can I take the former approach and not the latter even with the new feats? Sure.
Will I? Based on my experience with 4E, sadly no. Will most DMs allow the former if they use the feats but the people haven't taken them? I doubt it.