You're just digging yourself a hole here, Ostia.
Quoted from FFWiki:
In Final Fantasy IX Crystals are the source of all life; the Crystals residing at the center of planets circulate life, from which all life is born, and to which the souls return upon death, and as the memories of living beings accumulate inside the Crystals, the planets grow. Eidolons in Gaia are guardian spirits created by the Crystal in order to protect it.
The people of Terra had mastered the art of fusing their Crystal with others, allowing them to assimilate other worlds and keep their race thriving even when their current Crystal weakened. As revealed in the Final Fantasy 20th Anniversary Ultimania, once a Crystal has aged, it returns to the cosmos and becomes the source of a new Crystal.
Crystals also appear in the game as a means of summoning Eidolons. The four "jewels" sought by Queen Brahne of Alexandria were in fact fragments of a Crystal broken apart 500 years prior to the game. If all four jewels would come together in Alexandria, Alexander would be summoned. This echoes Final Fantasy IV, as Alexander heavily resembles the Giant of Babil, which was also summoned by a gathering of Crystals.
Also, Crystals can be equipped as Add-ons, which grant the user special abilities, particularly for Dagger and Eiko, who can learn Summon Magic from them. Eiko can also alter her Summon Magic according to the gemstone she has equipped.
The game was based on Crystals - even if they weren't shoving the theme in your face every time you open the menu. Perhaps you should be the one to replay the game.
The game was based on Life and Death, and that was the focus of the game, the crystal theme was a secondary one, it dint consume the storyline as in IV-V, it was never the catalyst for the storyline, again for the first half of the game, crystals dont really mater at all until the end of the second CD, and even then is "Oh alexandrias crystal is broken... cool lets hit on dagger and move on" the only other point where the crystal meters is in terra at the end of the game, and then you are on your merry way to finish the game and it's wonderfully written end boss :/
To compare IV-V-III to IX is totally idiotic, **** if all we need to say a final fintasy was based on crystals is for it to be a minor plot point linked to the main point of the storyline, then VII was also based on crystals, materia is created from the lifestream, the lifestream is the essence of the spirits and life, OH MY GAWD FFVII WAS ABOUT CRYSTALS!!! YOU CAN EVEN EQUIP IT