Student vs professional is usually a difference in pigment and pigment amounts, the binders are typically the same. So, from that respect, I wouldn't expect a lot of difference in the important aspect of their behavior.
So, watercolor pencils are designed to be used dry on dry or as a wet medium, so there's no inherent reason not to use them for dry coloring, they just have different characteristics versus more traditional colored pencil medium and you can learn to take advantage of those just as easily. This is true in "normal" options as well, the behavior of wax-based is different that oil-based, and you can use that to your advantage.
In terms of getting brighter, this is also true of wax/oil pencils when blended with a blender. You're dissolving the binder, leaving behind the pigment, and that usually results in a brighter look. Binder differences can result in a difference of brightness dry, but that doesn't necessarily mean the pigments are richer.
The biggest difference, in my still limited observation working with Polychromos and Albrecht Dürer pencils, is that the watercolors blend together much, much, easier and I need far less layering to achieve coverage once I activate with water. In fact, for a single color, one is generally enough. It's a different look though, as it's not opaque, but that's the fun part of watercolors.
So, sure, you can use the watercolor pencils for dry coloring. Just remember that if you want to use them wet, the paper matters. Normal dry paper is probably not going to hold up that well to applying water.
