What's that make the katyusha then? You can easily dodge 3/4 of the rockets if you're paying attention. And "just move" is BS, you can easily lose team weapons even if you move them right away. Not likes there's flares telling you where they are falling...
Really don't think any artillery unit should ignore the LoS and range rules that effect the rest of them
There is a non negligible difference between the time on target of a Stuka and a Katusha.
Furthermore due to the line of the Stuka and the limited number of rockets, moving in 9/10 directions and youll be fine, that is not true with a circle of a katusha.