pming
Legend
Hiya, again. 
I think what it's going to boil down to in the end is "group style". For us, in our experience, over time players tended to create characters that got sucked into "standard Feats" for any particular trope. If you wanted to make a Fighter (Champion) who used a two handed sword...are you going to take GWM, or Skilled? If you were making a Ranger (Hunter), was the choice really that hard between Mounted Combat, or Sharpshooter?
Now, of course a player could take the 'less optimal' choice for his character concept, but the moment the PC encounters an equal leveled NPC (or PC) who does have the 'optimal' feat in question...well, the more diverse characters spotlight is dimmed significantly. Your "two handed brute" is suddenly quite a bit worse than "that in-shape guard guy over there" because the guard has GWM and you don't. Your elven bowmaster is good, but not nearly as good as the human thief who has Sharpshooter. Your heavily armored dwarven cleric is suddenly in need a much more healing than the heavily armored gnome who has Heavy Armor Mastery. That was the kind of thing we were seeing. If a Feat existed for some particular "concept", you were all but forced to take it.
However, without Feats, a fighter with a two handed sword and another fighter with a two handed sword were equally "as good" as the other; now the things that made them better/different/unique was their personalities and the players playing them. With feats, both players had to either have, or not have, GWM; the moment one took it, the other had the stigma of 'second-fiddle'...why send in Bill when Bob is exactly the same, except he has the option of -5/+10 on his attack?
Certain play groups would obviously not care one way or the other about this. Our group fits mostly into this category. However, after time, it did get...annoying. The inclusion of Feats wasn't granting more 'fun', it was causing more un-spoken resentment and annoyance. And, as a DM, I found that I had to start thinking more of character Feats than about logical and cool story stuff. I had to specifically place "PC-specific" challenges. This sort of adventure writing just sucked all the fun out of it for me. I don't "build encounters" to fit my players PC's. My adventures are built with virtually nothing but the most broad PC capabilities in my head (e.g. "the're mostly human and about level 4"). I don't care if there are no fighters, or three clerics, or no outdoorsy types...if the PC's go investigate "The Haunted Halls of the Zombie Lord" and they don't have a cleric or paladin...not my problem. But when Feats were being used, I found myself thinking about the players PC's as much as I was about the internal consistency of my campaign world. And that sucked. Didn't like it one bit.
Anyway, play on! Feats are fine for those that want the extra work and don't mind adding more and more (because Feats are like crack to some players; they are always looking for the next, bigger, "high" of some particular character optimization build). Thankfully, 5e wasn't designed with Feats and MC as a base.
^_^
Paul L. Ming

On the other hand, now you have a group where all of your Fighters and Barbarians have no feats. How is that more diverse?
Not saying you're wrong about feats-no-adding-diversity. Am questioning the logic of your decision, however. I would have thought feats and no feats can both lead to undiverse characters, so how about combating the real issue at play here: which likely is groupthink among your players...
Cheers![]()
I think what it's going to boil down to in the end is "group style". For us, in our experience, over time players tended to create characters that got sucked into "standard Feats" for any particular trope. If you wanted to make a Fighter (Champion) who used a two handed sword...are you going to take GWM, or Skilled? If you were making a Ranger (Hunter), was the choice really that hard between Mounted Combat, or Sharpshooter?
Now, of course a player could take the 'less optimal' choice for his character concept, but the moment the PC encounters an equal leveled NPC (or PC) who does have the 'optimal' feat in question...well, the more diverse characters spotlight is dimmed significantly. Your "two handed brute" is suddenly quite a bit worse than "that in-shape guard guy over there" because the guard has GWM and you don't. Your elven bowmaster is good, but not nearly as good as the human thief who has Sharpshooter. Your heavily armored dwarven cleric is suddenly in need a much more healing than the heavily armored gnome who has Heavy Armor Mastery. That was the kind of thing we were seeing. If a Feat existed for some particular "concept", you were all but forced to take it.
However, without Feats, a fighter with a two handed sword and another fighter with a two handed sword were equally "as good" as the other; now the things that made them better/different/unique was their personalities and the players playing them. With feats, both players had to either have, or not have, GWM; the moment one took it, the other had the stigma of 'second-fiddle'...why send in Bill when Bob is exactly the same, except he has the option of -5/+10 on his attack?
Certain play groups would obviously not care one way or the other about this. Our group fits mostly into this category. However, after time, it did get...annoying. The inclusion of Feats wasn't granting more 'fun', it was causing more un-spoken resentment and annoyance. And, as a DM, I found that I had to start thinking more of character Feats than about logical and cool story stuff. I had to specifically place "PC-specific" challenges. This sort of adventure writing just sucked all the fun out of it for me. I don't "build encounters" to fit my players PC's. My adventures are built with virtually nothing but the most broad PC capabilities in my head (e.g. "the're mostly human and about level 4"). I don't care if there are no fighters, or three clerics, or no outdoorsy types...if the PC's go investigate "The Haunted Halls of the Zombie Lord" and they don't have a cleric or paladin...not my problem. But when Feats were being used, I found myself thinking about the players PC's as much as I was about the internal consistency of my campaign world. And that sucked. Didn't like it one bit.
Anyway, play on! Feats are fine for those that want the extra work and don't mind adding more and more (because Feats are like crack to some players; they are always looking for the next, bigger, "high" of some particular character optimization build). Thankfully, 5e wasn't designed with Feats and MC as a base.

^_^
Paul L. Ming