Nebulosity question

[mickw]

I understand why I am getting B&W fits from nebulosity now - it's because I am saving images in Raw mode rather than 32 bit Maxim something

What I don't understand is Why bother with saving Raw and then demosaicing before I can do anything with them.
It seems simpler just to save in 32 bit thingy

So what is it I'm doing wrong or not understanding ?