Yoshi-P frequently mentions that he is trying to make FFXIV a more "Final Fantasy-esque" game. On top of that, 2 hour abilities were a really cool feature in FFXI that made jobs much more individualized and fun. So, why not introduce something similar in FFXIV, but rather than 2 hour abilities, call them Limit Breaks, like in Final Fantasies of the past? Limit Breaks are an iconic part of many FF games that I feel would fit perfectly in this game, and you would be killing two birds with one stone: making classes more unique AND making the game more Final Fantasy-esque.

Here's one example of how it would work: each class (of course, including crafting and gathering classes) gets its own unique Limit Break. Possibly, you could learn additional Limit Breaks as your rank increased or certain other conditions were met. Then, in addition to your HP, MP, and TP gauges, you would have a Limit gauge that slowly filled up as you defeated monsters, caused damage, crafted items, etc. When the gauge fills up, you are able to use a powerful skill that can turn the tides of battle...or crafting, I guess.