I agree with him on sequels, it's one of the declines in gaming(as well in movies and some books). Instead of making new original games with original mechanics, worlds.. companies just reskin the same shit over and over again, sometimes with subtle improvements between each game, sometimes worse, it kills innovation and creativity. The same happens with some books and movies where they release shit tons of filler sequels, just because the first one was sucessful, thus creating a profitable brand. This makes a game, a movie or a book less 'art' and more like products to sell, imagine if there was Mona Lisa 2?
Fallout would be perfect if just ended with the first one, same with Baldur's Gate, Gothic, Diablo, Dark Souls, The Elder Scrolls, System Shock... these games did not need sequels, that does not mean that the sequels for these games are bad, most are better, but the effort could've been put making a new game instead. Yeah, we would have lost great games but think about what we could have gained if companies focused on making new IPs instead of making sequels.
Of course i know making new IPs every time is not viable from a business standpoint.
So my respect for Cain for understanding this, he wanted to create art and not just products.