No no no, abso-freaking-lutely not.

Heirlooms completely ruined the leveling experience in WoW. Even disregarding the exp boost (which you already get plenty of in FFXIV), they are just rediculously overstatted and completely take away the enjoyment of gathering new equipment. As for your "Otherwise it's just potd to powerlevel" argument, people would do that regardless of whether or not there are heirlooms.

Say no to heirlooms, say yes to people actually playing the game.