I don't believe the point had anything to do with ifconfig vs. ip. Rather, it's no longer possible for people doing remote troubleshooting to make an educated guess what the name of the interface in question is.
Imagine destining to the lay user how to read and parse the bits from the ip command output that you're after. Now, instead of knowing it's the add-on card and asking for bits of "ip addr show eth1", you're now along them to run "ip addr" and figure out which of the devices might be what you're looking for.
In another scenario, system automation doesn't often involve management of network interfaces, but it's also not rare. I had been able to look at DCIM and know what address ethX would have assigned. At the moment, I'm not really sure how to handle the new naming scheme. I miss simple and (globally) predictable.