Just had the same issue flying to PVG. This is where BA wins hands down - First & Club World allow 3 bags max 23kg each (32kg until 30 Sept 07) irrespective of route. Even WT+ allows more than the VS UC limit[n]
My sister had flown out with BA for work and was amazed when she learnt of the VS limit "But I thought you were flying Upper?"
You should be OK if it comes in at 32kgs, went going home via HKG our bags from HKG-SYD were 32kgs and 33kgs, and they were fine. As long as it is not over 32kg as the baggage handlers won't lift it.
Good, we managed a 35kg this year, Jimbob247 Jnr started wailing at just the right time! It's a crap policy though (the 30kg), especially as the flight is only half full...
Mixture of cargo, competition, profitability and consumer power is my guess, or just because they can. VS is merely following the market on this one I believe it applies to all carriers.
There's a plane at JFK, to fly you back from far away all those dark and frantic transatlantic miles