Weakness In Wing Chun?

Eddie Chong on Rollback/Armbreak

Glen Hairston Rollback/arm break

Sam Masich Rollback/bar/break

I'd like to be clear about this, because these comparisons are general in nature and we are talking about differences between striking and grappling arts.
With that said, I believe that Wing Chun players tend to carry their center very high in their body structure. This may be because of the close range hitting and play of Chi Sao (sticky hands), and "climbing" over the other guys guard. This combined with off-angle hitting tends to pull the center up with rapid punching power mostly generated from the shoulders. At a Wing Chun seminar, my friend was paired up with a very muscular guy with fast hands. In Chi Sao, my friend could not defeat his hitting, so he began up-rooting him with the Tai Chi Chuan push, and the guy couldn't maintain his root to continue hitting. Now, this is all very general but I think it points out a weakness in Wing Chun.
Take a look at this video of Nathan from TDA Training (guest posting at Mokuren Dojo). In Western boxing, the boxer ROOTS down into the hit, maintaining his connection to the ground. Many times in Wing Chun, I see the person hitting nearly up on his toes, at least on one foot. Additionally, Wing Chun's strength, adherance to toe-to-toe centerline concepts, may also limit mobility in neutralization. Compare Eddie Chong's arm bar/break to the others to see what I mean.
All-in-all, I see Wing Chun as powerful and effective, and some of these comparison's may be off-base. I am fascinated by the hand trapping, and will continue to explore these ideas.
*(Edit.) Upon edit, I see I posted Nathan's hook punch video earlier, so I found the boxing video HERE. Note that even when Nathan lifts his heel in the cross, hook or uppercut, he is driving down into the ground to develop power. This produces different energy than Wing Chun "chain" punching.