I have an aversion to rooting my Nexus 7. 'Rooting' in NZ is a slang word that (amongst other things) means 'wrecking'!
I use both Nexus Media Importer and Nexus Photo Viewer from the Google Playstore without any apparent problems as far as my purposes are concerned - getting files on to my Nexus 7 (I also use Dropbox for this purpose) or viewing them on the Nexus/showing them to others when I travel, and most of all, for the expansion of the memory capacity of the Nexus 7. I haven't found any limitations thus far.
I bought an OTG-USB adapter - cost just over $US2.00 for a pair, and free delivery to NZ from here: http://dx.com/p/micro-usb-on-the-go-...ter-pair-50774
Everything just worked as soon as I plugged in the adapter and pen drive. So simple, so easy to carry when I travel, no more tangling cords. Of course it works better when working in landscape, but I am not finding any particular difficulty with the combo sticking down towards me when working in portrait mode.