Or let them come with 3 Black Spirit Claws so we don't have to waste 70mil trying to preorder them from the MP just to maximize the effectiveness of the Outfit pls :)

I believe that they are a non-essential addition to the outfits, the crystals you can add to the outfits have little impact to gameplay. I don't think they will be adding claws to the packs since they are also used as a key in grind spots.

At end game, Having the ability to put +2 move speed in your pearl outfit is most definately a benefit.  Urugons have +1 move speed, Cron meal has +2 move speed, putting +2 move speed into your pearl outfit, means that you can run Frenzy Draught (0 move speed, 0 crit) and Spirit Perfume (+5 crit) and get +5 attack speed, +5 move speed, and +5 crit freeing up a boot crystal for something else more useful.

Rather than giving out 3 black spirit claw pieces, just have them come with a black spirit claw, or the crystal slot prepunched.  Alternately allow us to spend loyalties/pearls to get the Black Spirit Claw (not pieces) to add a socket to the outfit.  

"Dealing more damage have little impact."

I don't think.

Altrough I don't think that they sohuld give free slot. They should only adjust the price limit on claw, so ppl can buy it.