It’s not about the killing, they’re already dead Jim...so there is no source of new mammoth ivory making it a valuable paleontological asset that could disappear and so should be preserved; not cut up to hang from the ears of the modern day Marie Antoinette.
Do you day the same about golf and silver?
This isn’t rare. That is why you can buy jewelry made from it for less than $50.
When you can buy pieces for $35 a POUND, there isn’t a shortage.
http://www.mammothivory.info/p.aspx?p=249