This is why I said you were correct AND wrong. Let's just assume everything what you said is correct. So what's the result? Why do people choose SK over DW? Only for PvP? No. That's because SK is better than DW in every respect.
Your argument is theoretically/ideally plausible. However, having two tanks in a party is not efficient at all. Furthermore, unlike you have maintained that SK is a boss-tank, SK has more and better skills to fight against mobs (AoE skills) than DW does. Please do not deny this fact. Plus, you seem to have misunderstood about taunt. If you are spamming a taunt skill to maintain aggro, please don't do that. That's a very dangerous idea (I won't explain why). Draconic protection is not as good as you may think. TBH, not practical at all.
So, you are right in that DW and SK are different and must be differentiated. No one would disagree with that. In reality, however, people choose SK over DW because it is way better in all respects. SK can do whatever DW can do, but not vice versa. Why do you not accept the fact?
sSMETESs I really do enjoy good discussion with you and trust me, we are on same page with this.
I just do not want to take away true role of DW and that is large group of mobs tanking.
Still, "spamming taunts do nothing", just make all mobs focus on you, taunt, as SK I do that all time when ever I see that someone in my party is in bad position, that is what taunts do, save people (mostly fighters or turtles lol).
Still what got in my eye is "SK can do whatever DW can do, but not vice versa", not true.
SK can't tank large ammount of mobs, for long time, while DW can, that is thing.
DW was made to be tankish version of turtle, but his dmg is reduced cuz he is just too good tank.
Now, DW needs to be edited to be half good as turtle aka (large group killer), that was his role.
Still thx to his tank side, he can be on boss and spam taunts and keep aggro on himself, when aggro go away.
How to help DW, it is really easy, with few skill edits:
1. Dragon's Punishment (based on success rate) - max level, heal 2k per mob fixed with 30 CD and 500 EP. (let them spam)
2. Powerfull Roar - increase range to 35 m, on 25 targets.
3. Energy Siege - Needs to be based on success rate and not hit rate and with no critic 3 - 4k dmg, ofc if you increase wep will be more.
And with Great Defense passive, DW should be decent in dmg making.