Charging uniformly across territories is definitely an advantage* for points. Publishers on PSN can seem to charge whatever they damn well please for different regions with the same content. I know there have been complaints about Dragon Age Origins: Awakening recently, snd Sony even advised them to lower the price.
That's not intrinsic to points. There's a money-to-points ratio for each currency, meaning different regions will pay different amounts. With cash, an exchange rate could be fixed at the same rate as you would points. eg. In a 'fair' system, all customer pay the same. For points, you'd price the points at a local pricepoint relative to international currency value. Let's say $1 = 100 points. European customers could be billed €0.75 for 100 points, and Latvistonians Drogba's, it could be D1500 for 100 points. Buying 100 point item would cost the same relative dollar amount for everyone. In cash, you could bill the US customers $1, EU customers 75 cents, and Latvistonians 1500 Drogba. Cash or point makes no difference.
Likewise you can have regional price difference. For cash, just charge different amounts - $1, 75 eurocents, or only 150 Drogba. The Latvistonians get it for one tenth the price! Or with points, charge $1 for 100 ponits, 75 eurocents for 100 points, and 150 Drogba for 100 point. That 100 point game is 100 points everywhere, but the regional price difference is still there.
The difference with Sony's system I think is that they allow the publishers to set their price with no hard limits, allowing for regional price differences. And these regional price differences are part of commerce due to selling to local economies. They exist everywhere else (CE goods, services, etc.) so why shouldn't they with content? Not that I'm saying they should or not, only that there are regional price difference due to regional economies.
And there's no trying to get a better deal on different stores either because DLC is region locked.
That's not an issue of cash versus points!
With $$$$, you get discounts on the games directly.
What's to stop someone discounting game prices in points? "Buy Zombie Massacre. Was 500 points, now 300 points!"
With points, you can buy points at a discount (i.e., park your money with the vendor for them to make collective interests), and then you have another opportunity for game discount.
You can buy cash cards at a discount too. I've seen £50 PSN cards for £46. Points are just more sensible for discounted cards, because it sounds a bit crazy to get money for less money!
Overall I think there's virtually no difference in what the systems offer. At the end of the day points are just another currency, and buying points is like buying foreign money's to go shopping abroad. There are no intrinsic limits to the services you have to provide with either system. Excepting maybe certain legal issues with dealing with money, which I don't know anything about. But for the end users, the possibilities of discounts, bonuses, and regional price variations are a factor of the service providers and publishers, and not at all tied to the payment method.