But it requires a lot of hand strength as well to keep all the notes ringing clear for the duration of that part. I do agree the subtle details matter, but strength still counts too
My experience (and I'm a woman with childlike small hands...):
Even for this chord you don't need very much strength, but the right technique and of course a well playable guitar with a fine set up. I can play this chord and the melody even without the help of the thumb!
Why do you use a straight index finger in this situation?
For me this chord is much easier with a bowed index finger. A straight index-finger isn't necessary, because you need pressure of the barre-finger only for the outward strings 1,2 and 6!
I just don't want to waste any power...
Another hint, maybe helpful for you, too:
For my small hand it's nearly impossible to play the melody note on the 11th fret in the "right way" with the tip of the pinkie und keep simultaneously the barre-notes clear.
My solution: I play this melody note more with the side of my (stretched) pinkie.