Reasons to Kickstarter Carmageddon.
Marketing - you just need to see the comments here, on Kickstarter and anywhere else that only those who really pay attention to gaming news (probably of them, those who read RPS) knew this remake was in development. It has already generated loads of news posts on sites etc.
Speed - they state in the video that they think the more money they can get, the faster development will go.
Independence - even if they managed to find a publisher which let them keep the ip, independently funded and independently published will mean they get to make it just as controversial as they desire.
I can see no reason why they wouldn't Kickstarter this, it seems a good move for them.
I am however a bit dubious about their ability to make a good game. They haven't really done much since Carmageddon. Which wasn't just a controversial game when it came out, it was also a bloody good driving game. Possibly the best of its time, people look back it now and think it looks a bit cartoony but every game did back then! This should be looking amazing while also squishing pedestrians. I'm not sure this is going to..