I am sure many people would pay the higher fee, even if it's 10%(?), to get funded instantly and avoid going to a bank.
Is there something I'm missing?
The problem is that people intending to commit fraud would flock to such a service. So even though the majority of buyers are probably honest, the service would have a higher percentage of fraud than conventional methods.
I still think it could work if the marketing targeted Bitcoin newcomers who are intimidated by having to use their bank account, but the marrkup may have to be more like 15% with a cap at $250 per purchase to ensure profit.
My bank charges me for direct access.
A debit card is not considered direct access, though it's basically the same thing, but I don't have to pay a fee.
It's not so much intimidation as it is that I really like not having to pay 12% of the transfer in banking fees, with a minimum bank transfer amount of USD$85 (above the maximum transfer amount for one exchange, FWIW). Seriously, it's just not feasible to require a bank transfer unless I'm going all-in like some people (Rick Falkvinge, for example).
It would make more sense to charge a 5% fee for debit card purchases, because they operate with the convenience of a credit card but are required funds. Add a 3-5 day wait for the funds to clear, and it's a good model for business (at the very least, better than what it is right now).