I suggest that there be a way to save a predefined mapping of skills on the skillbar (6 to 0) so that you can change your spec while out of combat. I use a Guardian and I find that it’s better for me to specialize my skills per mob set or boss in a dungeon.
For example, in Ascalonian Catacombs, it’s best to have Wall of Reflection and Sanctuary when you hit the part with those small spiders but when you get to the Graveling Stalkers and Howlers it’s better to have stability skills like Stand Your Ground. What I do is that after certain parts of the dungeon where I am out of combat, I would quickly change out the skills but I have to do it one by one. If perhaps the whole skill bar can be toggled between different sets that would be easier. Lineage II had this and you would toggle by doing Alt – #.
The same can be done with weapon sets. For a Guardian running Twilight Arbor, it’s best to have a Staff for the plants that you need to AoE and also a scepter for handling the mobs that aren’t good to melee such as the final boss. But there are a couple of bosses that you can actually take on using a Greatsword or a Mace/Shield. I also do the swapping out of combat and have to do it manually. This is very tedious but I think the versatility is something that is innate in the game. There’s no one size fits all solution to the game.
As you can see, the uses of this extends out of the dungeon context. You wouldn’t use the same sort of skills or weapons in WvW as you would in a Jormag run or a dungeon run. As players get more proficient with their characters, they will naturally customize builds. I have friends who continually re-trait for different types of runs and not just swap out armor sets.