There is definitely some room for expanding the available bone enforcements. Below is a list of suggestions for drop-only bones. The intent with these bones is multi-purposed. Some drop from mobs you are already killing and not looting, some drop from mobs that you'd otherwise skip over.
Hoverbot Headbone - (Drops from Hoverbot)
TL 83, Str: 83
PSR:+13.28
T-C: +9.96
Soldier Chest Enforcement - (Drops from Chaos Soldier)
TL 57, Str: 57
END: +13.43
PSN: +10.05
Personal Repair Arm Enforcement - (Drops from Beserk Copbot in Gaia Mine)
TL 38, Str: 38
REP: +6.70
IMP: +6.70
Mauler Leg Enforcement -(Drops from Terrormauler)
TL 60, Str: 60
TRA: + 9.69
FOR: +14.50
Spider Queen Foot - (Drops from Spider Queen)
TL 13, Str 13
AGL: +3.21
ATH: +3.21
If there are comments or objections to a specific item I can reply further but figured I'd just toss them out there first to see if anyone liked them.