European (EU) buyers prefer websites where they are not charged VAT Tax (20%+-)

Porn isn't FOREX so it is best to price your goods in the buyer's 'home' currency -- he understands that value.
Sellers by user IP, or the payment processors for sellers by the credit card used issuing bank location, just convert the purchase price to buyers' currencies.
Dollars are not that cheap today -- the Euro value against the US Dollar has fallen from $1.40 to $1.13 or so +- in the past year.