Rylai's Crystal Scepter and Frozen Mallet

So I've been seeing a lot of dev discussion surrounding Rylai's Crystal Scepter and Frozen Mallet for a while now and the problems the two items present, and I was wondering why the possibility of removal of those items hasn't come up yet.

I feel like it's very difficult to have a world where those items are allowed to exist and either useless/100% pickups, especially in a case like Rylai's Crystal Scepter (if every spell slows and it gives as much AP as all the other strong AP items along with a bucketload of health, why wouldn't I build it?)

Wouldn't it be easier to evaluate whether or not a champion SHOULD have spell/autoattack slows, give them that accordingly, and remove those items from the game?

Edit: Also, there are certain champions that are based around the consistent application of slows as a core part of their kit (Ashe, Karma, Lissandra), and given that slows no longer stack, having a strong iteration of Rylai's Crystal Scepter pushes those champions out of selection because why take a slowing champion when you could have a more damaging champion that slows anyways?