Currency conversion fees are a fact of life no matter which payment processor is used (though some may offer better/worse rates at any given time). Even PayPal charges fees.
By offering different currencies, Chrono would essentially have to pay the fees for you (since they need USD in the end). So, either they take a hit in profits by paying everyone’s fees, or they raise the non-USD prices to cover the fees (but to keep the same profit, they’d have to raise them by more than the fees would be, since the fees would be a % of the new price, which means you’d actually end up paying more).
Having the customer pay the currency conversion fee is the least painful option for all involved.
More payment options would be good though! The particularly thrifty could choose their payment method on who has the best rate that day.