The potential my friend. When we have genuine Gen3 products you will be able to measure the difference. Right now there is nothing that is truly Gen3 and certainly nothing that will max out the bandwidth of Gen2. It is all about bandwidth by the way.
And to honestly answer your question as to why - marketing speak. Has no real benefit at all but folks will want it because it is 'new', does nothing different with current hardware.
To help us help you - please provide as much information about your system and the problem as possible.