Make Rylai's and Mallet legendary items

I would like to see the Frozen Mallet and Rylai's Crystal Scepter be built from an Advanced item so they are made into Legendary items.

Item:

Frozen Grip - costs 1200g - made from 2 Ruby Crystals and 400HP and adds the following active ability: Activate to slow an enemy champion by 30% for 1.5 seconds. 30 second cooldown. 400 Range.

This would have a net increase in either scenario when upgraded to a Frozen Mallet or a Rylai's Crystal Scepter due to the ability to then rapidly apply the slow.

Currently I feel that Giant's Belt is too punishing a building block item to get these completed items.