Change Melee, Ranged, and Magic buffs to all.  We don't need Melee accuracy, magic accuracy, and Ranged accuracy, same with AP, no need for Melee AP, Ranged AP, and Magic AP, this just makes the grind artificially longer and more annoying than it needs to be.  

I understand the DR and Evasion, that makes sense to force a choice, however the buffs since only Maewa and Musa use Ranged and Melee there is no point in adding extra artifacts to the buff stats.  

Keep the specialized Life Skill artifacts, the way they are.

Kinda punishes you for tagging certain classes.

this is a bad thing?

its 2 birds with 1 stone, more inventory clutter and more build "variety" 

The illusion of choice.

On the defensive side it is more variety, you are correct.  On the offensive side however, there is no diversity.  A Ranger is only ever going to use ranged AP and ranged accuracy, melee and magic AP and accuracy would be useless stats to a Ranger since all their damage is ranged.

IMHO, the game shouldn't even have ranged, melee, and magic AP in general, just like it shouldnt't have MP, SP, and WP. Each class always has the same thing, and having it not match between classes is pointless and irritating when it comes to recovery items and items that affect those stats. It's like if they had Ranger AP, Maehwa AP, Berserker AP, etc., only they were "kind" enough to restrict it to three variations instead of one per class. It should have just been one.