Don't forget that when a merchant like WordPress receives PayPal payment from customers in other countries, they get charged "cross border fees" of an additional amount (~1% extra).
 - https://www.paypal.com/us/cgi-bin/?cmd=_display-xborder-fees-outside


This also lets WordPress customers take advantage of the frequent opportunity to arbitrage.  There will be instances where the price (in USDs) is more expensive to pay than if that customer were to buy bitcoins using the local rate for bitcoins due to exchanges not always being price efficient.

For instance, at this moment BTC/USD is $11.52.  So if I was making a $11.52 purchase from WordPress, I would be asked to pay 1.0 BTC.    At this moment the EUR/USD is 1.2727 and let's say the BTC/EUR was 8.7 EUR.  That would let the customer pay using bitcoins and see a discount versus if paying using EURs, as those 8.7 EUR would convert to $11.02 USD using the current EUR/USD exchange rate but they buy 1.0 BTC which satisfies the amount on the WordPress invoice.

These differences will normally only be a few percent but there are times (like today) where these opportunities to perform purchase price arbitrage are possible to the WordPress customer.

Additionally, WordPress (or parent Automaticc) likely pays freelancers for help and those freelancers will probably be among the first to realize that if WordPress is accepting bitcoins that WordPress might also be willing to send payment in bitcoins as well (versus whatever current method is used -- such as an expensive bank wire).    When that happens WordPress may just change their payout conversion settings so that some of the revenues are kept as BTCs.

It may already be that WordPress is paying for help (e.g., freelancers) with bitcoins, and now adding bitcoins as a payment method for its revenue stream gives them a cheaper method to acquire bitcoins than buying through an exchange.     That's probably not the case here with WordPress, but this undoubtedly will be the catalyst triggering much follow-on commerce where bitcoins are used for payment.