Couple of points to make here
Obviously ever prior Sony DSLR has been CF, so users will be pretty well stocked up on those. Now it's no shock that Sony have changed formats for the lower end stuff. On the other hand, does it really matter so much? Cost is very low for half decent cards, unlike 6 or 7 years ago when they were pretty pricey. I don't believe a format change will have much impact myself.
It could prove a slight annoyance to some, though SD is popular..and I have a few lying about (well more than a few), it's another type of card to carry, that won't work on your previous bodies.
Thus IMO CF and SD solves the issue, and would please current users more.
A note to the Doc, I am well known for not being a MS fan, but I have no problem with the format, or the fact sony started it. Truth is, and it's undeniable, SD is "the" main format, and is used extensively in many other non camera devices. In a perfect world, we would have had just one format card. SD is now king (why or how or if matter not) MS is of next to no use in non Sony products. IMO Sony should have the guts to just drop it, and follow the SD path. We're stuck with dual slots with one card format that is of less use to users (MS), for no other reason, than Sony are too stubborn to admit it didn't work! I'll wager anyone, the vast majority of new users buying these 5 new bodies, will be using SD a lot more than MS