Melding is definitely one of the worst things in FFXIV (gosh how many times have I used this expression...)

I wish every failure will give you a stacking buff that increases the success rate of your next meld for that specific materia. Even if only by 1% each failure.

Well at least it's better than a certain Sci-Fi setting MMORPG where failing a "meld" will clear all other "melds" on your equipment...