It is true that .223 is used by NATO, but 7.62x39 IS available in EVERY country, legally or otherwise. The military adopted .223 to give the grunt more ammo for the same weight- the difference in bullet weight alone, for a standard combat load of 300 rounds, is 3.4 pounds. Given that, the grunt can carry twice the amount of .223 vs .308 for the same weight penalty.
As to price, every Internet source I've searched and in every gun show I attend, .223 is at least 1.5 times more expensive than 7.62x39, including the Russian stuff in both calibers. If there is a source that is cheaper, share it with the community. As far as reloading either one goes, I can't do it cheaper than I can buy them already made, even considering the prices.
Regarding fragmentation, .223 does not fragment in FMJ configuration (aka military hardball); it TUMBLES on impact. This was designed into the round to compensate for the lesser static shock versus that of the .308- which by the way is most definitely NOT an inaccurate round. Just ask a USMC sniper or Camp Perry competitor.
All military hardball, regardless of caliber, will leave a "caliber size" hole, unless bone is hit. Using a frangible or expanding bullet does increase temporary wound cavity size, but that applies in all cases. Using a larger bullet will result in a larger temporary wound cavity; the size and weight makes up for the speed differences.
.223 would not be my choice for hunting anything larger than coyotes, unless I limit myself to headshots only, and I sure wouldn't use it on hogs! I've seen our local walking bullet traps soak up hits from a .300 WinMag and keep going! For those critters, I use my Beowulf now.