In all honesty? It might.

Let's say one of those jobs is Samurai; pretty unique job there, and a lot of people might consider buying the game JUST to play as a Samurai. Well, if they're unable to play a Samurai until they're 60+ hours into the game? Well, they might opt to just not even try FFXIV.

Like I said, that's exactly what happened to me with the Blue Mage in FFXI. If you're already max level, I think it's awesome to give them a head start on leveling a new job, but newcomers still want to be able to access those jobs. After all, New Jobs are a major selling point to any expansion, and if the buy said expansion, they're going to be eager to play then right away.