It does, at $20B cost. A simpler JWST that takes advantage of the large fairing of Starship will cost less and take less time to build

You know what costs even less? Building a larger fairing.

Atlas V has different fairing sizes for different payload types as well.

Sure, a bigger fairing will simplify a space telescope, but you still need to fold it and the bulk of the costs went into developing instruments and the mirror.

There's nothing "simple" about a state-of-the-art scientific instrument. If you want Hubble 2.0, NASA has two of them just lying around for over a decade now; gifted to them by the NRO.

You know how much converting them to useful scientific instruments costs? According to the latest report, it's about $3.2 billion so please give me a break with your "simpler and cheaper because fairing".