It also helps that the US is a large market with lots of people with disposable income.
But make no mistake: if they thought they could make more money(/it was better for the business) to launch it somewhere else first, that's where it would have happened.
The US market should be a good indicator on how many units will be sold in other regions, I suppose. Plus sending over a few thousand units to Europe would probably just increase frustration about it not being available when they were sold out. I guess it takes a while to set up a supply chain for a new product that they had no idea about how many people would go for.
It's an interesting business decision: Developing/Penetrating a (perhaps the most important world-wide) market deeply is more important to them than opening up new markets sooner rather than later.
It's the usual modus operandi as far as Apple is concerned. Non-US Apple users and developers like me are getting used to this by now but it is nonetheless quite disappointing.
