The 120mm mortar does have solid range, but one must keep in mind that because scatter scales due to distance it simply cannot be used effectively at long range. If players want to score consistent hits with mortars they must be within roughly one screen length of distance whether the mortar is 8cm, 8.2cm, or 120cm. Any time you see a replay of 120mm mortars owning face it is almost a certainty that they are doing so at very close ranges.
this is the problem with only looking at a few stats. youre completely ignoring AOE. youre also ignoring the differences between the auto fire and barrage. distance scatter max/ratio make the 120mm mortar excel at auto firing, while the 82mm is better when barraging.
You have noted the 120mm mortar's high damage output. Are you aware that a 120mm mortar does 6.14 dps while a barraging vet0 German 8cm mortar does 18.82 dps? Are you even aware that the German mortar has three times the DPS? Don't even ask what dps an elite troops insta-vet 3 german mortar puts out... The reality, and the numbers, show that while a lucky 120mm hit is potent this is mostly due to perception and smaller german squad sizes. The 120mm mortar fires extremely slowly and its ability to influence a game is inconsistent for its cost.
care to explain how you got your numbers? because your 120mm dps is way off.