There will be many, many accessories soon enough, including, I would expect card readers that play nicely with The Nexus 7 and USB OTG. Some of the ones out there may do so already. Looking through my own kit, I have a wired hub, a portable drive, a 64GB memory stick, a card reader--lots of shtuff. I'm guessing that a $10 cable will work with many of these on the rare occasions that might need them to.
Let's not lose track of the fact that there doesn't have to be one true way of looking at this. Different people require different features. As my granny would say, "there's a lid for every pot."