Ok, I think you can copy Federer. In the end it's just bio-mechanics and if it's the most economical, I'm sure people will study it and use it. Dimitrov uses similar technique, right?
But, you are right that you can't copy Fed's style, technique is useless without tennis IQ, tactics, creativity.
Look people can copy Whitney singing technique too, but they will never be as great as her, because why she was great was because she was the first, she invented it.
Why can't you copy both? You can combine Fed's technique with Djokovic style. This is how evolution works, players create some hybrids. Fed is a hybrid of Agassi and Pete, so I'm sure guys in the future will be some hybrids of Fed and Djokovic.
But we can't know for sure which style would be popular. Maybe some genius will come and reinvent serve an volley again. Imagine a Nadal type guy who just practices serve and volley fanatically since age 6 for thousands of hours, maybe he could beat the baseliners.
I'm just going by what the 6-8 different coaches have intimated. When you begin tennis very young you play with 2H's on both sides, the modern style of topspin involves a lot of mini-tennis, where the flexibility of young kids taking those balls routinely above their shoulders is honed. As you fill out open stance/semi to western grips become more natural.
I'm not saying this is right or correct, its what they push out in the academies and schools for kids that need to very quickly be able to rally to live out the dreams of their parents. Not one coach or academy [I've been to] uses Federer or Nadal as a model to emulate, the prototype is always Djokovic when it comes to groundstrokes and footwork. In fact, most coaches I've been across specifically dissuade using Federer as a model, that needs a lot of time and yes, even a racquet which by today's standards is out of place.
9.99 people out of 10 will use a sub 320g racquet, for Federer kind of strokes you first need to be committed to heavier frames.
EDIT
Though Federer is by far the most analyzed player on YouTube etc, lets be honest, for people that are very invested in coaching and learning the game though years of development, its a different type of journey. Everyone could use a thing or two from Federer, and I'm completely confident no aspiring tennis player - whatever their level - hasn't looked at some video of his and thought "I can do that", but really, its not at all a simple thing. You need to have exceptional tennis skill to think of going there.
Much simpler to opt for Djokovic if the idea is to quickly get results, which most people that are investing hours and $$$ are looking for from their effort on court.