Having different weapons equippable on a class != the skillups needing to take forever. It was indeed a slow painful process in XI, but that doesn't mean it couldn't be made faster. I didn't like the time it took either but I enjoyed the variety of different play styles I could use while still being on one class (and still different from other classes also using the same weapons, since you're using the different abilities in combination with the weapons), even if some were really only useful as solo. It was flexible and balanced (with jobs having "preferred" weapons still), just slow is all IMO.
That said, you're also right that we'll probably never see it for XIV. The armory system is here to stay and classes being tied to weapons is just how it will be.