Your wrong in terms of how VIM came about and name.
VIM originally meant "Vi IMitation". It wasn't till 1993 that it became "Vi Improved."
Actually VIM is not a direct fork of VI. VIM comes from Stevie editor from Atari ST and Amiga days. (I actually started with Stevie).
Here is the tree from ed to VIM
ed > Bill Joy and company then made em > en > ex AKA vi
Joy left development of VI in June 1979 and joined corporate life working with BSD.
vi (Unix\BSD) > Stevie editor (Atari ST) > VIM (Amiga)
Then chaos hit. From 1981 onward clones and implementations were incompatible and progress kind of grind to a halt due to license. That is when Stevie editor hit and then when Bram Moolenaar made VIM. He reimplimented it for Amiga and added features one being plugins. Vi had no plugins and very little customization.
Here is why your analogy is wrong: LICENSING "While commercial vendors could work with Bill Joy's codebase (and continue to use it today), many people could not. Because Joy had begun with Ken Thompson's ed editor, ex and vi were derivative works and could not be distributed except to people who had an AT&T source license."
So it is not at all like this fork. I find that people have taken sides without even knowing the history of VIM and make assumptions.