it could be that the way desynthesis worked before the change - CUL desynth wasn't particularly useful past ARR stuffs and since only fish increases CUL desynth levels it was probably seen as too much work for too little reward.

but it could be changed back now that desynthesis has changed. it's just a matter of whether or not the devs want to put rewards behind desynth or not. it seems most good glams are either mogstation or made via treasure dungeon rare mat drops.