Credit card transactions are reversible and the numbers are easy to steal, so it would be too easy to scam an exchange in this way. It's just as hard to convert local currency into any other currency, so it's not really unique to Bitcoin, and it probably won't get much more "effortless".
It is easier to write anti-fraud algorithms for other goods: If you want to buy stuff and ship to Romania with a US credit card, that will raise a lot of read flags I'd imagine.
You also have to resell the goods which is probably quite a hassle. There are of course a things that are almost as good as money, like gold and stuff, but the sellers of that probably have their algos set for very few false positives.
I think the way you could probably do this is that you could let people buy using credit cards, but then not actually give them the bitcoins until the credit card chargeback timeline expired. The risk is obviously that as the exchange operator you become a bitcoin speculator because you're holding bitcoins that may not end up being paid for by a customer, so not a good idea with the volatility we are seeing, but I think that's the only way credit cards would work.
I think it depends on why people are buying the coins. If they are buying them to hold them, then it does not really matter. I think there are a lot of people out there who just want to quickly grab some Bitcoins and hold them for the long term. Often times for those people their biggest concern is getting in before it goes up any more, so this would be a solution for them.
But if you're going to be holding onto them for years, an extra couple minutes to link your bank account to Coinbase shouldn't be a big deal. The difference in price over the initial two day validation period is going to be negligible over the course of 5 years.