You're suggesting defensive tactics get a premium commander unit in the form of the KV-2 which is no small feat to be honest, while if this was implemented the Wehr one would suck even more, I mean, why choose to play Wehr with all of it's shitty abilities compared to the awesome Soviet one? You get a .50 cal MG that shreds light vehicles, the best indirect fire support weapon in the game in the form of the 120mm mortar, trenches or whatever if they're combined, impassible tank traps and the KV-2 tank, compared to trenches, tank traps, hull down, Pak 43 which is probably the best thing about this doc, and Sector Arty which as you said is situational.
And yes I am very well aware that such abilities are often combined for the Western Front Armies but not for the East which is very puzzling for me, but still I can't explain to myself why the lack of basic field defense such as the sandbags for the Wehrmacht, a supposedly defensive Army as Relic have already stated with their info-graph or whatever.
My only suggestion is that if they were to really actually add the KV-2 to the Soviet defensive doctrine they should compensate the Wehrmacht with the Lefh 18 as well.
Just wanted to point out a few things.
1. The DSHK HMG does ok against light vehicles, not amazing. It's a soft-counter, if anything.
2. Like AussieMagic pointed out, the 120 mm mortar has seen some changes. It's still good, but not great.
3. Tank traps can be targeted and destroyed by tanks. (Quite easily, I believe. It just takes a little more micro.)