Than go and buy a better prime... I do not prefer the whole picture blurred against sharp isolated subject.Sharpness and overall IQ is the main reason to use primes for me. (even in "enough light" situations)I'm saying regardless of cost, I'm asking would you prefer to carry around one set or the other. Is the weight worth the sharpnessYou seem to miss the point of using prime lenses. Its more depth of field, and low light needs that drive users to primes. Sharpness has less to do with it.
If I'm shooting in very low light, I have little choice. Same if I want very shallow depth of field, f/2.8 might not be enough.
Many primes are as sharp or sharper than zooms, not a big issue for me.
Zoom I use only in a situation I know I do not have enough time / space / clean place to exchange lenses.
Thus "...weight worth..." - yes it is! ;-)
My 50L is not sharper than my 24-70 f2.8 II @ 50mm f2.8 nor f1.2
Better bokeh is what we looking for in primes
+ all my primes used for stills are sharper @ 2.8 than 24-70II@50, F2.8...
PS: Your 50 is only acceptable in the center, but I usually do not prefer center composition...