You can make fun of my comment if you wish, but the Kat is supposed to provide you with a help to defeat the elephant. If you are T4 you need a long range unit to wear down the elephant, the kat can fill that role.
Yes penetration is worse, but they can prevent elephant from being repaired and force it to move. They also let you know where it is in the FOW.
then in the same sense, panzerwerfer is soft counter to isu?