Ummm... let's see... USF has CalliOP and Priest, incendiary attacks, pack howie, of map artillery;
UKF has Sexton, base howies, off map artillery;
OH has PZwerfer, howie and off map artillery;
OKW has wurframen and off map artillery;
Soviets have katiushas, howies, B4 and incendiary attacks.
Did I miss something?!
Well you should not get your mortars to close, because it's dangerous. In fact, don't get any unit to close, because it's to freakin' dangerous. Is that a reason?
If you don't want to use mortars, fine, pick one of above, at your liking.
List the decent offmaps ostheer has again please. You want to use ost howi? We both know that thing is a waste of manpower. That leave pwerfer. Very fragile lots of scatter at safe range, comes later than any other for of artillery (especially if you want any armor from t3), and delays any other tanks you want/need to counter enemy tanks. Youre cheap FRPs have relatively hard to get and expensive counters.
Offmaps are doctrinal and shouldn't be needed to counter doctrinal abilities imo.
Another example of this is USFs need for Calliope's and priests for a form of heavy indirect fire.
The only time you're gonna suffer from a stuka bomb is when you aren't listening to the plane overhead and you make no effort at at all to move. All risk about the FRPs for USFs can be easily avoided by repositioning. OKW has to slug out its choice so their is alot more risk to it as you said.
Listen Johnny, nobody is saying there is no counter play to FRPs. What the problem is, is that it comes too late and still has such a huge impact on bigger maps that it can often prevent the enemy from even getting counters to it at all. It promotes blobbing as well which I think you'd agree with, needs toning down.