First thing first: what we're saying is that a subclass feature that gives you a bonus actions is more difficult to minmax with a feat than subclass features that gives you stuff not in the form of bonus actions.
I don't see how that is anything more than an opinion. Certainly not defensible with any kind of hard facts. Just conjecture and assumption.
In the top strata of minmaxing you're not short of bonus actions. If anything, you run the risk of having too many (sources of) bonus actions. Since, you know, you can only use one at a time.
Bonus actions to do
what, exactly? Because having more than one way to use your bonus action is not 'waste'. Its diversification. Its flexibility.
I can tell you this from experience. My assassin/shadow monk/feypact warlock has a slew of bonus action options. All great. All very useful. In varied and different ways. I'm rarely without a satisfying thing to do with my bonus action. If all I had was "hit it again," there'd be many circumstances in actual play where I would have missed out on using my bonus action effectively.
Why don't YOU provide an example of the feat you want to take instead of the one we're "wasting" on the bonus action?
How about, while you are taking whatever bonus action attack feat you need to catch up to me, I'll take Sentinel (now I'll get more opportunities to make reaction attacks!). Or Alert (Never surprised, and didn't someone just mention how devastating it is not to go first...). Or, heck, I could just take +2 CON (more HPs, +1 Con saves, +1 AC).
Let's call that comparison d (to couple it with my previos post):
d1) One Totem Barb and one Berserk Barb, both with the PM feat (say)
d2) One Totem Barb and one Berserk Barb, both with the CC feat (where CC = ChrisCarlson)
]This then allows you to see the comparison between the Totem Barb of d1 and the Berserk Barb of d2.
This infatuation with requiring two characters--
built differently--to take the same feat keeps missing the point. When they reach a point to access a feat, they are each given a discrete option. No different than when they were given a choice at 3rd level to pick their path. These discrete choices are what separate characters, and even their players.
And you keep wanting to make sure these two intentionally divergent PCs make arbitrarily similar choices, in a key place designed to customize and separate from others, just so that you can prove one is better than the other? That's not how things work.