It's one of those thing that's "cool to hate", I guess.
I have never once had anyone complain about the font. I suppose it's possible that someone out there found TWB for the first time and went "Ew! Comic Sans! I'm not gonna read that!" but somehow I doubt it.
Now, I do remember, years ago- about the time I started putting the shadow around the strip- considering whipping up a custom font. There were services that would take a sample of your handwriting and turn it into a TrueType font, but as i recall most of them were fairly expensive.
And, I have horrible penmanship. The resulting font would in all likelihood look worse than Comic Sans, so I figured why bother?