As is common with any ethnic group, the diaspora is typically more nationalistic than those living in the actual country of origin. Mix that with historical revisionism, and you have a recipe for what the Skops did in Australia last week.
We can speak endlessly of the ineptitude of the Greek government since the 1990's regarding the issue, but the unfortunate truth is that any solution right now would mean that FYROM keeps the name Macedonia in their country's names. If this is going to be the case, the Greeks have to make sure the agreed upon name is some kind of composite than can't be dropped in everyday conversation.
Here in the states, you see that this issue is compounded by the fact that most Greeks don't really know any better and refer to our lovely neighbors as "Macedonians." Might just be where I'm from since most of the Greeks here are 2nd or 3rd generation from places like Tripoli and the nisia, so there isn't a familial connection to Makedonia.