1. Because PSN is owned by Sony, not Square Enix. Thus before SE could have adventurer recruitment made through the PSN Friend List, they would have to clear it with Sony first, which I presume, SE has probably decided would be too much trouble than it's worth).
2. Because FFXIV ARR is a PvE game - the PvP elements available are separate from the main game and are not an integral aspect of it. Games which have 1x1 PvP usually are based around that style of gameplay, or else it's so unbalanced it usually just breaks things. If you're hoping that ARR is based around PvP you'll be sadly disappointed.