Well that's your opinion. It's working great and sounds great to me and millions of others so not sure what to tell ya?
Fair enough. Use what works for you. Maybe FAS can make the model more true, to your ear.
And I might add, that even though I don't like that amp. or its distortion, to me, ANY sound is potentially useful. Some of the cheeziest effects I've ever had, which just MAULED the sound, still proved useful at times (usually in application for which they were expressly not designed, like on a nose flute or an acoustic piano). That's why I have so much of my old stuff: amps, effects, instruments, because you never know when a Foxx Tone Machine with the tone set to 'ear bleed' is just what you'll want.
Creative aural molestation makes any old thing potentially useful (I once did a 'tubular bells' kinda thing playing a whisk through several effects).
Doubtless if I had a JC-120, I'd find an occasional use for it, for its own brand of oddness.