1.) Because a remake is totally unnecessary. Why bother? What's the point? Is the original not enough? Was the not-completely-crap sequel not enough? Why would you think going back to the well a third time would somehow magically improve things? Don't you think that maybe there might be something else interesting that you haven't even imagined yet -- but someone else has -- waiting to be discovered? MY GOD MAN, HAVE YOU NO SENSE OF WONDER ANYMORE?!!!
2.) Blues Brothers 2000.
3.) Because a sequel or a "reboot" is totally unnecessary. A new cast doing basically what the old cast already did in some "going into business" film, plus one or two sequels of ever increasing budgets and ever decreasing quality.
4.) Blues Brothers 2000.
5.) Because all this is is two basic bad impulses. The studio's bad impulse to cash in on a brand name wherever possible, and the fans' bad impulse to chase the same high they had once and will never have again. Let it go. Enjoy the past for what it was and find something new to enjoy in addition to this instead of trying to wring laughs out of a long-dead franchise.
6.) No, seriously. Blues Brothers 2000.
I've got one thing that I'd like to point out to you:
Ghostbusters: The Video Game proves that there's still a potential for the franchise. The story is better than
Ghostbusters II (which tried to play too close to the first film. In fact, a user on YouTube asked the question why
Ghostbusters II was getting a bad rap, and I explained not in
one, but two different video replies, the
second one being at the request of the user. Despite playing too close to the original, it had some pluses). The game took what was presented in the first film and expanded on it, gave us something new that differed from the first film, much like how
Aliens (which played more like a war movie) differed from
Alien (which was was like a sci-fi/horror version of
10 Little Indians). If the second film had the story that the game had, I bet the second film would have done better. Actually, Gene Siskel and Roger Ebert gave the film two thumbs down and were disappointed that the film didn't try anything new (where as the game actually presented something new, even by expanding what we were introduced to in the first film. To me, the second film was almost as good as the first one (and I like it), but it could have been better storywise (and the video game actually proves it), which makes me wonder if the reason why the film's story is the same is because of the studio forcing the filmmakers to use almost the same story instead of allowing them to take the film in the direction they wanted to.
Now, since Dan Aykroyd has stated that they're going to have new recruits in the film, it opens a big door for potentially good storylines (not to mention ongoing details from the first two films and the game). As a writer, the fact that Aykroyd is okay with bringing in some new blood opens the door wide for potential story ideas for what'd be like for the Ghostbusters of the 21st Century. For example, as a writer and if I were writing the story, I would have Oscar Barrett, Dana's son (who we last saw in
Ghostbusters II), now all grown up has decided to join up with the Ghostbusters against his mother's wishes (which leads Dana back into Peter Venkman's life once again). Around this time, someone possessed by Tiamat, a primordial goddess of the ocean in Babylonian mythology, finds the Tablet of Destinies, a mythical Mesopotamian clay tablet that is said that whomever holds it rules the universe (which the table had once been hers). As a result, reality is fractured into multiple realms that lead to different periods of time of Earth's history and the only people not affected by present day being wiped out are the original Ghostbusters, Dana and the new recruits because of some new equipment that Egon and Ray were testing inside the firehouse (which remains unaffected while modern New York and every other city in the world being erased from existance). In order to restore reality back to the way it was, the new recruits and the original Ghostbusters have to work together to defeat Tiamat through different time periods and eventually restoring things back to the way they were. Is it a great idea for a story? Maybe not, but its one possibility that comes from the introduction of new recruits, while being able to have a lot more characters to relate to both for the young audience and the original fans of the
Ghostbusters films.
But to address the question of "Why have another one?" Well, it's primarily because there's a demand for it with the original audience. Much like why they did
TRON: Legacy, there was a big demand for it from the fans for over 20 years (despite the fact the first one didn't do well at the box office). So, instead of allowing fans to take over and do a
Ghostbusters film (which many have done as fan films, one of the better examples being the Denver Ghostbusters fan films, in particular
The Return of the Ghostbusters), the original filmmakers and the studio sees that there is more of a demand for it than the next, mindless Michael Baysplosion spectacular.