As I see it , the real advantage is for use in replacing existing receptacles in existing construction. I believe it is the intent to require such a receptacle to be used in repairs to non-AFCI-protected circuits after the next code cycle.
(Guess that means they'll want them to be tamper-resistant as well. Can this possible become more of a cluster-flock than it already is?)
Likewise, the 'first receptacle' business allows us to add AFCI protection to an old home that has a fuse box or obsolete panel. Since the expressed purpose of these gizmos is to prevent fires from frayed wiring, it seems logical that it's the OLD homes that need them the most.
There's a certain amount of BS in the distribution chain. When AFCI's were first introduced, Leviton was swearing, and the UL plant inspector verified, that they had pallets of these things in the warehouse. Yet, Graybar was telling me that they were 'not available.' I ran into a similar issue with CED. Only several months after the AFCI requirement was locally adopted did the things suddenly become 'available.'
It's not the only item where the supply house, and the manufacturer, had differing views. Heck, I've often encountered different views between the manufacturers and their own advertising. Sometimes I'm amazed that anything ever reaches the intended user!