Is it possible to use OTG Cables for Nexus-4 without rooting the device? Can Nexus Media Importer work with OTG cables for Nexus4?
The Nexus 4 does not support USB-On-The-Go. From the Nexus Media Importer description on Google Play it states that:
Due to hardware limitations, the Nexus 4 is not supported.
The only way to get it to work is to root and install a custom ROM and/or kernel. You will also need a usb y cable as the Nexus 4 cannot provide the necessary 5 volts. Android Central has a page with more information