A divided fanbase is natural and should be expected. There's no IP or franchise that has ever been completely united in desire, interest, or what they do not like, as evidenced by the Bond movies, Star Trek TV shows and films, Star Wars, etc. IP holders may want a hive-minded audience, but that has never been a reality in the history of film, TV, or any other medium, as someone--or group will see any particular production as the worst trash ever hurled at a screen, while others think its gold running out of a camera.
That's all true, which is why the Gunn-verse success will depend on those outside the fandom. Of course, Gunn has his own fans at this point--but, his DCEU effort didn't exactly break box office records. WB wants those big numbers at this point and will not settle for less, so the pressure is now on Gunn to create something really special that will bring audiences out.
I actually agree, but the Marvel (& DC) suits will inevitably want Tony Stark and Bruce Wayne, and they and the shareholders will get it.
Our best hope will be that the creatives will make a decent job of it.
What's interesting about that is that Iron Man was not a major Marvel character prior to the 2008 movie's breakout success. At that point, Marvel was pulling from their less well know characters because Fantastic Four, Spider-Man, and X-Men were all franchises they couldn't use. It is very possible that the future of the MCU may be more FF and X-centric--and that has the potential to be highly successful.