Neither the Yuan Renminbi (CNY) nor the Russian rouble are "convertible" currencies. I have never been sure of the exact legal/technical meaning of this, but one cannot just buy them in a bureau de change in other countries, generally. I've lived in both those countries and one shouldn't give the impression that everything is easy with banking there, far from it!
It is, I agree, very strange if few American banks allow deposits or accounts denominated in Euros, for example. I remember when I lived in Europe it was easy to do the reverse; but then it was Luxembourg, which is a banking centre.
I also wanted to make a practical suggestion - by opening a forex trading account at
www.oanda.com (just one possible company, there are others, I just happen to be a happy customer of theirs) you can ask your account to be denominated in your home currency, or dollars, or euros, and you can express your opinion by holding positions in other countries' currencies. Leverage is available if you actually want to trade, but of course you don't have to use it; you can just use it to hedge risks.
However this practical suggestion will not allow you to buy roubles or RMB (the latter is not even tradeable in any normal way on the forex market yet) .. as I say not convertible and so on. Roubles can be traded somewhere, though ..