That kind of a risk is a good thing though as it removes materia and gear from the market, forcing people to make/buy more. Plus all those people who like to look down on others for not having 5 materia gear can feel special again, they were crying pretty hard about previous things making gear easier to get
Why not have it like XI? Because this isn't XI. The devs can do better than XI, and I personally feel they are in this system. It's not as complicated as you're making it out to be.
1. Use gear until it has 100% spiritbind.
2. Convert gear into materia
3. Attach materia.
4. Rinse/repeat as desired.
Simple.