I agree with this, but I think it's only part of a bigger issue. The off-maps in general are a bit unbalanced since the WFA ones are comparably stronger than the older ones. To bring them in line they received some massive changes to be somewhat similar to the original ones, but this definitely needs some finetuning. Instead of just focusing on the USF artillery I'd rather in general do a complete pass over all the off-map abilities as there are problems that are not just USF related and if you do them all at once you might be able to balance them better. Just to denote a few:
- Ostheer Light Artillery Barrage destroying (not decrewing) static artillery
- Ostheer Sector Arty being more or less useless and incredibly map dependent
- Ostheer Strafe
- Ostheer Anti Tank Strafe
- Soviet Incendiary Artillery
- Mark Target
- A ton of those single-pass strafes
And probably a lot more I just forgot 
Doing a complete overhaul of the entire off-map call in system is just asking for trouble. Incremental change is better. I'm not asking for anything huge here, just some small tweaks to existing values.
I'm also not saying those abilities are perfect. However, if they do need some attention, they probably deserve their own threads.