Suggestion: Add a separate tech line to upgrade ground unit racial attack.
Rationale: Currently, GU racial attack is improved by the "caliber" tech for Lasers, Railguns, Plasma, and Particle Beams. This means that if a race wants to use missiles, Gauss, HPM, or Mesons as their main weapon(s), their ground units will be basically screwed unless they invest into one of the former four weapon types. This can be worked around most easily by developing plasma weapons, but it seems silly to force a race to do this if it is not within the player's roleplay canon for that race, and it adds an extra RP burden at the start of the game if the player wants to stay within the allocated starting RP. Basically, the current mechanics effectively are a nerf to missiles and mesons, neither of which needs the extra hurting in the current state of Aurora.
Additionally, this mechanism can upset GU balance if the player chooses to research very cheap Plasma weapons to boost GU attack, as the low RP cost means that GU racial attack can easily reach ~50% greater than racial armor, which tends to upset the ground combat balance in a way that minimizes the value of armor and reduces interesting decision-making as a result - ground combat is intrinsically balanced around the expectation that racial attack and armor are usually equal at a given nominal tech level. I don't think it is good for interesting gameplay decisions to be flattened if the player decides they want plasma guns for their ships - note that plasma is just fine for ships and doesn't need to be a special bonus for ground forces to be useful or viable.
Finally, while this isn't really a rationale for a gameplay change, I will observe that for DB modders it is not possible to change the ship armor techs without affecting the ground unit balance. Pulling GU attack into its own tech line would allow a DB modder to rebalance GU attack if they decide to change the ship armor techs.