The use of brackets is not unique to the UK, the company I work for in the USA uses them almost exclusively in its financial reporting.
Thank you for confirming this; I too have seen US accounting documents that use brackets, but was not sure how widespread the practice was in the US.
I know that this is on the list for resolution, but there have been two Service Packs since I raised the matter. I think that the programmers understand that the lack of this feature creates a compatibility problem. What they seem to understand less well is that, certainly in UK accounting circles, using anything other than brackets for negative numbers in accounting documents is a no-no, and, as you say, this makes an otherwise excellent program unusable for many people's purposes. If I were in their shoes, I'd be putting a great deal more urgency behind this issue than has so far been evident.