I won’t be at all surprised if this was suggested before, it’s kinda obvious.
If the players are provided with the ability to change skills, then they should also be provided with tools that would help them do it efficiently. If a player wants to switch between game styles; if he wants to be a Bonder, Healer, Trapper, Interrupter, Stancer. If he wants to play pvp or pve or simply go farming. All these options require you to start dragging skills from the menu to the skill bar; an extremely tiresome and unnecessary task that could have easily been avoided.
The solution is Skill Sets - a way for you to predetermine several groups of skills, and the ability to move easily between them. The simplest way to implant it is to place a line of skill tabs over the skill bar. These tabs will only appear in town and will allow you to set and switch between skills combinations. Simple and convenient.
Y

i used mr search button (my friend but you can use him) and turned up skill sets of all varients over 4 pages of threads including several closed as completely redundent. (like this one)