The problem with the Panzerwerfer is its limited area of effect. It is designed to have a chance of wiping 1 unit. Nothing more. Now if you want to play mind games with your enemy (targeting vs dodging) the werfer will be a failure more often than any other arty since you only cover that small area. In the end the Werfer is dodged more easily.
Secondly the Werfer has to deal with large Soviet formations (6 men crewsand sqauds) that cover huge areas. A Werfer will not push that formation away.
It comes down to the role of the Werfer not being needed. Ost needs area denial arty, not pinpoint accurate arty (which the Werfer fails to do aswell at times).
The LeFH doesnt really help much any longer since the reload overnerf. And Ost crutching on Tigers to compensate for non existant T4 means you cant go for the LeFH in the first place.
You seem to be under some weird, incomprehensible impression that werfer 10 scattering rockets land in area tighter then a single con squad spread, which isn't exactly that wide(comparable to gren spread on neutral ground).
Are you sure you are talking about the correct unit?
We are talking about ost rocket arty, not mortar halftruck, just to get you back on track.