It was present in FFTA/A2 as well. You'd equip an item, use it for (x) time/battles and you'd get the skill from it. The only problem with the original system, in regards to FFXIV, is that one weapon could teach multiple classes different skills. Obviously it's an easy tweak but just something to consider.

I think it's fine if it doesn't replace the current system. Kind of like, you get these skills 1-50 just leveling and then these other skills are special and require a little more work.

Edit: Also it wouldn't be too bad on the market with the heavy influence on crafting in this game. I mean I'm in a decent sized LS and we've got crafters for most everything so if someone needs something made it can get done in a few days usually. Exceptions obviously being the real high end stuff like Silver Tricorne, 50 weapons, etc...