Prior to their return in Spider-Man: No Way Home , some of the classic Spider-Man villains had never been used in the MCU.
Indeed, No Way Home goes so far as to specify that Norman Osborn does not exist in the MCU, although in the past there have been rumors that stated otherwise. In general, Doc Ock, Goblin, Electro, Lizard and Sandman have never been rewritten or reworked for the current Spider-Man movie cycle, and there is a reason for this choice.
Marvel Studios boss Kevin Feige talked about it in a recent featurette. Feige basically explains that the idea was not to repeat and always look for original ways:
When we got the chance to bring Spider-Man into the MCU with Homecoming , we decided to explore two things that had never been explored before in the Spidey movies. The first was to make him much younger, [Peter] is in the early years of high school and has to deal with the problems of that age and the powers. We really wanted to enjoy the high school setting. The other was to set the films in the larger Marvel Universe, where other heroes exist. So for the first few films I always thought “How can we do things that have never been done before?”.
We never thought about remaking the story of Goblin or Oscorp, or remaking Doc Ock or any character we’ve already seen, that’s why the Vulture and Mysterio were the key characters. Even if those were the reasons, I’ve been saying for years, even before anyone asked me, that you couldn’t do better than Alfred Molina in the role of Doc Ock.
Who else but Alfred Molina?
Feige, who was an executive producer of Spider-Man 2 , the film in which Molina originally appeared, concludes:
It would have been difficult to take his place. And [I wondered] wouldn’t it be fun to find a way, if we ever had to bring Doc Ock back, to have Alfred Molina play it? And, when we started developing this third film in the Homecoming trilogy , we realized that, thanks to the MCU, there was a way to do it.
You can see the full featurette below.