I think of redwork as being an outline stitch, which was originally done in red. Like you, I have used many colors in a single project, and why the heck not? I am currently working on a project using black thread, and I thought about changing it up but then figured, I might get sick of any other color, and I don't want this one red, so I'm sticking with black. But I just as easily could have used lots of colors and that would have been nice.
I have a friend who I tried to get to embroider with me, but she thought it was too time-consuming. When she saw that I just outline and don't completely fill it in, she was more interested. Redwork is the only kind of embroidery I do, just not only in red!