I am pretty sure that 90% of people that get this commander get it because of the Sturmtiger.
The same people would get the commander it was moved to for the same reason.
Ofc 221 and Heat Shells are nice but overall it would be like removing B4 from Counterattacktactics. Also one needs one other commander that would need to give up one of his abilties in favor of ST ... and which commander should this be? Special OPs or Breakthrough? I am sure Command Panther or Jagdtiger + Tanks that have acess to HEAT + self repair would be a bit too strong
Not really. ST was a stock unit while B4 was unique to the commander from start.