It is very evident on the new-issue shirts, and looks nasty behind the tie when in No1 dress.
You may note (as an eagle-eyed tailor) that regular senior officers in No1s all appear to wear either old-issue shirts (so: no placket), or; they've invested in Double2-style placketless shirts.
Colour tends to be slightly-paler, and they're a finer weave (the shirts, that is, not the wearer!)
I fully understand the points you make regarding the intended function of the placket, but it does seriously look odd, behind ties, in many instances.
I wonder if it could be through-stitched, down it's full length along the wearer's left side (above & below your red pointer)? So that the placket doesn't look so obvious?