Judo is far easier to amalgamate into MMA because MMA has a strong grappling base in collegiate wrestling. Judo is effectively an alternative to wrestling.
Nitpicking, but I think there is a flaw in your logic. you see wrestling and grappling in MMA because it has proven to be a useful base in winning MMA. Judo is a form of grappling so therefore, it is easy to adapt those skill sets. It is not because MMA has a strong base in collegiate grappling. it is the inverse. wrestling did not inform or constrain MMA, it is simply that the rules of MMA are conducive to grapplers in general.
Nitpicking I know, and you probably actually meant to say what I said above. Sorry if so.