Hi Surfcandy!
I'm assuming that, by "scenario generator for the individual modules", you mean the specific Battle Generators (BGs) that were made available for quite a few modules right? Unfortunately, I can't really answer your question, as I never had those specific BGs in my hand (except the free HOTP BG PDF). When I was tasked with updating the generic BG 2.0, I started from there, as this was the only BG available.
From what I can tell, there was already quite a few 'systemic" differences between the specific BGs and the generic BG 2.0. My work consisted in integrating errata and clarifications from 2.0 into 2.1. I cannot speak of the "evolution" between the specific BGs and the generic BG 2.0
I guess my answer would be yes, if you are not looking into doing battles across modules (VC against Argentine, for example) and you are happy with the specific BGs, there is no point in buying the generic BG 2.1. But, from what I can tell, only the generic BG 2.1 will be supported from now on, as this is the most up to date BG.