It is not to say the OP's idea is a bad one. It just won't happen in FFXIV.

Everything in the game is formulaic, especially when it comes to gear. Main stat and Vitality are always "locked in place" based on iLvl. Ilvl also dictates the sum total of sub stats (with a few exceptions, such as relic weapons). You can pentameld crafted gear, but not tomestone gear or augmented crafted gear. The highest iLvl gear at level 90 will be replaced around 96. The same way level 80 gear would be replaced at 86, 70 at 76, etc.

So many aspects of the game are formulaic, not just gear. But, that goes well beyond a single post.