This isn't really an issue? The same happens with combat gear too. If you had your best of the best at lv50, it also overshot the new at the time HW handouts. (i130 Poetics gear vs i115 rainbow). For crafters, it probably even went a bit further as anyone doing well the 2.X patch series was probably also melded. (Some who probably used that gear far into HW, just as people wearing well-melding HW crafter/gatherer gear used that far into SB).

The 51-59 (and 61-69 for that matter) gear isn't designed to get you perfect chance HQs for at-level recipes.

Have your friends either get the older lv50 stuff and meld it, or grind on something older that they can use to gain a few more levels until the stat gap is more even, just like combat options. ...I kept all my melded accessories through the entire leveling process because they worked just fine. FFXIV has plenty of casual catch-up-ness in it.