From my experience conversion fee is almost gone (from online shopping) and most sites offer automatic currency conversion mostly for buyers conveniance to have an idea how much will cost in native currency.
World is divided into regions (just look at DVD's)
TBH, american company's started splitting markets into world regions and I'm quite happy to see (for once) US residents complaining over such bussiness model.
As for credit card dependance -- PayPal is not present worldwide and as such not preferred choice. Also, if you have PP account it's obvious you have credit card as it's required for basic operations.