You are sooo right about most listeners... a lot of them would not tell you any difference between a 200 dollar solid state and 2000 dollar valve amp, but who cares? If you are happy with your own tone, thats worth a lot =)
And, a big plus for BKPs: They all sound much clearer than most other pus out there.
A lot of people will not be able to tell differences because they have no comparison, BUT they will notice if your sound is undefined, muddy and they barely recognize the notes ;-)
So, end of story? BKPs help you and the audience 8)