This seems highly plausible to me.
So does this.
To me, it seems that the ways to make fighters mechanically more effective, without changing the way the play, are not entirely straightforward. I think it was
@doctorbadwolf who, upthread, suggested expanding Indomitability in both frequency of use and scope of use. That seems like a good idea that wouldn't change how they play. But it also does create some comparative weirdness potential - eg why can
the fighter do this but not the skill specialists like rogues, rangers, and bards? - so even a change like that is not risk-free.
The core design chassis of "why can't others do this thing?" is a genuine one. The obvious answer is to leave fighters alone and dial down the spell-users, but that hardly seems likely to make playing fighters even
more popular! It would just increase the number of irritated people.