I can see what they mean by more special attacks if I get this correctly. For example only Warriors and Thief that I can think of right now uses only F1 for specials. We can take Mesmer as another example on the other end. They have around four different ways to shatter their clones and that means they are using F1-4 for their specials.
I prefer sdf to move and apparently more and more people begin to catch on to this.
The reason for this is simple. You get a wider "reach" this way: You get an extra row to the right and extra row to the top. It's also more comfy since you can keep your hand in typing position and you don't have to bend your fingers where one is 'stretched'.