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.
