With the Brummbär changes there will be no reason to build it most games anymore. It will be counterd by PaK too easy. That was mainly why you built a Brummbär, too kill PaKs for your real tanks. Infantry is only a nice have to kill.
You build the Panzerwerfer to deal with ATG. The Brummbär is built for late game AI. The fact that it could 1v1 (or even 1v2) ATG frontally was a side effect of its unnaturally good combination of high AI power and high armor. No stock vehicle should counter ATG with so little effort for obvious reasons.