I would like dual spec simply for the convenience of having my alternative spec stored in order to make swapping them a bit less tedious. I don’t even personally care whether it costs gold.
As for winning an argument on the internet, meh. I had that won just as soon as you made the foolish statement that there aren’t hybrid specs because they suck. That’s simply not true. I mean shoot, 30/8/13 was a thing in vanilla for rogues specifically because it was a hybrid pvp pve crossover spec. In today’s min max culture, it is completely irrelevant, but it definitely was considered cookie cutter 15 years ago. With dual spec available, you can take it to the bank that a lot of raiding rogues would run something like that.
And that’s really the entire point. Right now many people won’t swap specs because it is a bit irritating to do so knowing full well that you have to redo it later and repurchase the skills. And they certainly aren’t going to feel at liberty to try alternate approaches within the class that are marginally worse at certain aspects of the game. Right now it really doesn’t matter because everyone and their dog is raid logging. But in tbc that meta won’t exist. Dual spec goes a long way toward allowing players the opportunity to explore alternative approaches within their class.
All that said, the counter point to this comes from post cataclysm when blizzard ditched the trees altogether. They said one of the primary reasons they did so was to make it so players could attempt to utilize more skills and that most of the player base had centered on a couple of primary specs within their class anyway. We don’t have percentages from back then, but guessing it was 90 percent or higher in cookie cutter specs.
So, there’s both arguments including a hearsay statement backing you up based on bad memory from the pre panda patch changes.