It failed why, because you said so? No arguement = Don't bother posting.
COH as a WW2 game is inspired by real life to a certain degree since it's the setting for the game, to the extent than a Tiger is better than a Sherman etc, it's the obvious fact of the matter. COH is not realistic, but is based on real things such as machine guns stopping mass infantry attacks (suppression mechanic) etc.
So you think panthers should get engine damage more than tigers then? Since panthers were less reliable compared to tigers.
Realism is not an argument. Appealing to relic's omniscience is not an argument either.
German tanks were on a whole less reliable, I'm not saying it's precisely realistic or should be. Tommies had grenades just like everybody else, but they don't in COH because Relic said so for gameplay reasons, it doesn't mean Relic thought Brits had less grenades than everybody else. It's entirely possible it was an inspiration for this vulnerability to being immobilised. And anyway the point in the end wasn't that it was realistic, but that Relic wanted Tigers to have this flaw and not other heavy tanks, contrary to the OPs views, because they are the ones who put it in.
And it doesn't matter what relic wants. Because EIR is a mod and has changed many things. Bren carrier armor/hp, AC armor, halftrack armor, treadbreaker, the list goes on and on. The devs have already stated they will make changes based on balance rather than trying to preserve vCoH mechanics.
This mechanic only makes balancing harder. If the tigers are too good after this change, then make this change and increase tigers' cost. Realism and "what relic intended" is never a good argument.