lynatic The reason for this is very simple. Normally, credit card companies (Visa, Mastercard, JCB, etc) want to charge a processing fee, and then the bank wants to charge a fee too. So if you buy say.. a toaster for $100, they actually charge the store $102 or more. When charging your Suica card from a credit card, it's never going to work if Japan Rail agrees to pay $102 and then charges your card for $100. While Bic Camera can absorb the $2 on the $100 toaster since it was probably making $20 in profit anyway, Japan Rail may may basically 0% profit since Suica can basically be used as cash (and even refunded for cash).
Therefore,instead of allowing all cards by default, JR specifically white-lists cards which that have an agreement with where they basically won't be charged any fees. The credit card will give up those juicy fees do this because JR is such a big player and being able to use Mobile Suica is such a big selling point in Japan - so I wouldn't expect any foreign banks. (The credit card company will also generally not give you and points, etc. for charging your Suica card - except of course for JRE and View Cards).
FYI: The mobile Suica support page lists all of the cards that will work.
I have a View Card (which can be set to automatically recharge), and actually haven't used Mobile Suica on my phone in years so it's possible some things could have changed - but I am sure credit card networks still want to charge fees, and JR still won't pay them, so the list of usable cards will still be a short one focused on Japanese banks.