This discussion apparently has been done to death, but what the hell, I'll thrown in my personal opinions just in case SE reads this thread. The materia system has a couple specific things that irk me about it right now:

1. The stat budget of materia is extremely high compared to the stat budget granted to the base gear stats themselves. It feels odd to have the materia be almost the only thing that matters when determining the total stats of an item.

2. Double melds seem to be becoming the "expected" norm for all players to achieve. Coupled with the top-to-bottom RNG-based nature of the materia system, this can become frustrating for players who aren't rolling in gil and can't afford to lose millions on failed melds. Could there be some way to reduce or eliminate the RNG aspect, but to increase the cost of materia acquisition and melding to compensate? (Perhaps something like increased spiritbond time, increased rarity of melding catalysts, introducing some other sort of cost to the melding process, etc.)