Fair enough, then you'll pay a lot more extra than the $3 for a USB adaptor. The Nexus 7 is really a "play and display" device, rather than a "create and store" device. (although you can do that)
Actually that's probably true of most small tablets. It probably costs them (and ultimately, you) more than it's worth to put in full-size USB and card ports.

I don't let my adaptor "hang there all day", any more than I would leave a USB stick in all day, I just keep it in my pocket or bag attached to the USB stick. In terms of inconvenience, it's right up there with taking my reading glasses off my nose.