In hindsight, yes. But I think after they got burnt with Ghost Starscream, they might have though 600 was as much of a risk as they were willing to take.
If they had toy buyers who knew where the interests lie, it might give them a better idea... but even then, it is just the collector community, and who would think that there would be at least 600 people (collectors/enthusiasts/dealers) in Australia who were desperate enough to want this particular toy this badly.
Unfortunately they had this order locked in with Hasbro about 6 months ago. So even with the 4 month delay, and lots of people chasing them up with release info (which they don't get with other toy items), they still didn't think it was worth increasing the original order... or, were unable to increase it.

Who knows. The head office isn't very forthcoming with answers. And the person in charge at the Garden City store was a bit "snappy", as she wasn't too keen on being corrected on the stats of how many Soundwaves Australia got, or how many TRU stores they have in Australia.