Personally I think your off the mark BDA.
The attacking roles players play will depend on their strengths. To say Pocock is a good attacker because he runs more, but just runs tighter and doesn't make breaks because of that is flawed.
Why does he run tighter?
Personally, if I was a coach structuring a team and I was telling one player to run tight and one to run loose it would be due to the fact that I don't see the tight runner capable of making many breaks, and I want him doing the grunt work, whilst I see another player capable of making breaks and I don't want him wasted doing grunt work which we can get any average attacker to do.
Now of course that doesn't mean it applies in this case because we are talking about 2 different coached teams using different tactics. BUT, if Pocock is runner inside the 10 channel a lot, and another Brumbies forward is running outside the 10 channel a bit, I'd be confident that is the reason.
I don't think it's a misconception that Pocock's not a strong attacking player at all. He plays like another tight forward in attack a lot, he doesn't put himself in the position to be an attacking threat so why would people ever see him as one? Now that may be down to coaching direction. Or it in fact may be down to himself thinking he doesn't offer much out wide, so just doing what he can to offer the most to the team.
That being said, if he continues to make line breaks and line break assists like he did last game, the perception of his attacking ability will certainly change.