You realize that you haven't lost anything, though, right? Your stat gains from these melded gears are either exactly the same or higher than they previously were. The only difference is that some of these stats now come from the gear itself rather than the materia you melded into them.

What you're doing is complaining about a net gain because it makes you feel like you wasted Gil on materia to pentameld. Try to think about it this way: this change allows you to get even more stats out of the same gear if you re-meld it.