If Classes are treated as separate Jobs, though, that's something totally different than the issues that Yoshi-P mentions. The problem he mentions, is two versions of the same job filling the same role. Instead, you would be presented something more like everyone having a DPS role, as well as a Healer or Tank form.

The only place it becomes confusing is with Arcanist, Summoner, and Scholar. Not sure how to handle that.

Also, I'm all about nostalgia. At the same time, FFXIV (or at least ARR) has managed to build a fascinating world and deep, interest story unique unto itself. The core Classes might not be "classic Final Fantasy Jobs", but I think their original incarnations were interesting enough to warrant a place beside classic Jobs. Classes are only "outdated" because they aren't relevant right now. Giving them unique roles, and perhaps even Artifact Armor, would give them a place in the game.