I remember I use to have an excellent crafting record for various items. For over a year I had only 1 failed Scorpion Harness synth.
Around the same time we had that massive gil bust, and the economy started going down, an unannounced change in the success rate of crafting showed face for all.
The change in success rate cost me over 30,000,000 G. My favorite aspect of the game did indeed turn to shit, so I put my account away last October. It's become very time consuming and frustrating to raise a measly 1,000,000.
My best guess is SquareEnix needs the game to be balanced for new comers, if the economy was suited for the rich players, the auction house prices will make it impossible for newbies to get their feet on the ground in short time, making FFXI extremely difficult to get into.
For the record i use to HQ Scorpion Harness 4 or 5 times a week. After the gil bust, 1/3 of my SH synths would break. sometimes 2/3, the following week.
This is no random change.