mattwnz:
I remember one reason for the deposit for first home buyers, was that it showed that the first home buyer was able to save. In fact I recall property experts saying that if people can't put together and save for a deposit, then they should wait until they are able to do this. This attitude from property experts seems to have changed in recent years, perhaps because it would take too long to save for a deposit these days, due to the high prices. It does seem people want things now, rather than waiting and saving.
When I was working at Westpac it was called hurt money. That's why you won't get a mortgage even if you have 50% deposit if it wasn't your savings. This may have changed as I haven't worked for a bank for a few years now. There was a whole thread on it here, I think the poster was trying to buy in Dargaville? And had a really grunty deposit that he was gifted.
The logic was that people who were gifted deposits were more likely to walk away from their home loan than someone who had saved the money up themselves.