In my mind its similar to a question of why use a pen, when you can paint with a brush. Vector apps like Xara, Illustrator, Inkscape work like using a pen - hard lines, defined shapes based on lines. Painting is a completely different animal. You need to perform tricks to get a brush to draw a hardline. A painting is nothing like a hand drawing - they are two very different styles. So the argument of whether to use a vector application versus an image editor has nothing to do with the qualities or tools in each program. In general the two create very different things - different styles. Some of us like to draw. Some of us like to paint (some like to do both.) I think of vector like drawing, and think image editor like painting. Truth is, I hate to paint, but I like the results of a good painting. So I accomplish both with the drawing tool, as it works best for me.
Really that's what your choice of software is all about - what works best for you. There is no one universal program to best create a map with - it is only dependant on what works best in your hands. Software is just a tool. We, the cartographers, are the artists - choose the artist's tool that works best for you.
PS: lots of software other than Adobe has CMYK functions built in - Xara does and it costs a fraction of what any Adobe program does. Don't let yourself be confused in thinking Adobe is for pros and others are not. I'm a pro and I hardly ever use Adobe products, in fact I create finished work in Xara, work in or export to CMYK (if needed) with final work ready for commercial printing or whatever the end-step is supposed to be. Saying Adobe is for professional work has little weight at all.