Perhaps the fees collected from merchants in the EU are no longer sufficient to support the fees. Can you post a link to the article?
That's my guess. While the EU's interchange fee cap doesn't actually apply to foreign cards, both Visa and MC charge only the 0.3% capped rate for card-present transactions, regardless of where the card was issued. Visa gets 1.5% on CNP transactions, hence the common surcharge for buying airline tickets with a foreign credit card. I think MC is similar.
With only 0.3% interchange, someone is getting a really bad deal when I use my American 2.5% cash back card to buy groceries every week.