That's interesting, didn't know that. Personally, I don't mind having such laws with all current and future products. It's a decent thing to do. But not allowing older products to be grandfathered in in some fashion just doesn't make sense in my opinion.
There are two problems with having ivory that is grandfathered in and legal. The first is that it there just isn't any practical and reliable way in most cases to tell pre-ban ivory from the banned ivory. There just simply isn't. And as you can imagine everybody always claims that their ivory (or item with ivory in it) is pre-ban even if the reality is that it came from an elephant poached illegally last year. It is way too easy to slip newly poached illegal ivory into the legal market and supply chain because there simply isn't a practical and effective way to reliably be able to differentiate between the two.
The second problem is that poaching will continue as long as ivory has any value, and ivory will always continue to have value as long as it can still be bought and sold relatively easily (whether or not it is legal to do so). If some ivory is grandfathered in, then ivory is certain to still retain value, particularly when it is allowed to be bought and sold. As long as there is any value to ivory then the poaching will continue.
As much as it sucks there are really only two choices here. If you want to save elephants, you must completely outlaw all buying and selling of all ivory regardless of source. This will almost completely kill the value of ivory and the market for it which is what will be required to stop the poaching. And it is possible that even this may not be enough and you may end up having to outlaw even the possession of any and all ivory as well, only time would tell. Only when ivory is made worthless and valueless through laws will the poaching stop.
Or you can allow anything short of outlawing all buying and selling of all ivory and have all wild elephants extinct within a relatively short few years. Period, end of story, no ifs, ands, or buts about it.
It is a tough choice for sure, and all comes down to what is more important to you:
--the ability to buy and sell some ivory
or
--having wild elephants on the earth instead of extinct
It is impossible to have both so pick one and get ready to deal with the consequences which really suck in both cases. You just have to decide which one sucks very slightly less than the alternative in your opinion.