Indeed, the original D2K siege tanks is absolute murder against infantry forces, and their presence largely neutered infantry hordes (both your enemies and your own, the original D2K siege tank splash damage is monstrous).
But while you can argue that it is the Original siege tanks who was op, in openRA, the very same behaviour could be found in RA Allied artilleries, and ironically, it's the D2K Siege tanks who end up weak, and only effective in their name role for sieging enemy bases (they're good at destroying buildings).
So, I want to suggest that the D2K Siege tank damage vs infantry to be increased, or at least having better supression effect on incoming horde of infantry. I'm still not sure about that though, if because those who played D2K isn't as experienced as RA players, but I'm sure if anyone want to prove D2K siege tanks is useful at their intended role against infantry, you're welcome to play MP with me
