Well, just because something is the most popular doesn’t mean it’s the best. Look at the highest grossing Hollywood blockbuster films–many are crap. 3D Max is by far the most famous 3D software in the world and has the largest user base, but for many years, it wasn’t even a contender for highend CG production. And if you look at music softwares, Fruityloops is probably the most used in the world, but it is nowhere near being the best music production software.
I’m not saying Photoshop is bad–far from it. I use it more than I use Painter, because I’m also a photographer, and other than getting the natural-looking brushwork and the awesome blending tools in Painter, I prefer to draw/paint in Photoshop because the UI’s more intuitive and making changes is much more efficient. However, it’s simply the truth that the smudge tool in Photoshop is absolute worst in all the drawing/painting softwares I’ve used. Photoshop was created for photo editinig–thus the name, “PHOTOshop.” But over the years they’ve added some nice brush tools, but at its heart, it’s still aimed for image editing, as that is Adobe’s largest market. Artists that draw and paint with Photoshop are but a minority in the grand scheme of things as far as Photoshop’s user base is concerned. This is why Adobe won’t really work hard at improving Photoshop for drawing/painting to the point of competing with Corel Painter or other softwares designed specifically for drawing/painting. They’ll always concentrate on improving the image-editing aspect as first priority.
