6. They Are Too Old
The last Ghostbusters film was released in 1989, and over the past 20 or so years, the original cast have aged quite a bit. The power of graphics allowed Aykroyd to set the video game in the 90s as a direct sequel to Ghostbusters 2, but Ghostbusters 3 has to be set decades after the originals because of the age of the actors. Whilst Ernie Hudson and Dan Aykroyd dont look too old, Bill Murray and Harold Ramis have aged considerably. Theres nothing wrong with this, as of course they were going to age after so many years and both are still great actors, but having Murray looking like an old man and Ramis gaining weight and somehow looking shorter (if it wasnt for his voice, I wouldnt have realised he was playing Seth Rogens dad in Knocked Up), it just wouldnt look right. Murray expressed this view himself when he was apparently quoted saying "No-one wants to pay money to see old, fat men chasing ghosts." Some people have suggested a way around this, however...