Mortars suffer from a few other problems. If you lose one man on the crew then they are one death away from a squad wipe. And if the squad wipe comes during retreat the weapon is lost too.
While this same mechanic exists for ATs there are some differences: First, the AT crew has its own built-in green cover. Second, since there is no retreat, the AT gun will stay on the field meaning you still potentially have that 280mp investment (Edit: And it can be repaired). This mortar crew vulnerability also means that US mortars are pretty vulnerable to the outranging Wehr mortar so many just aren't that keen on getting them, especially for 280mp.
MGs are cheaper at 240mp and much more survivable because they can survive the loss of two men in the crew (despite also being a crew served weapon).
I have no idea if the mortar mechanic can be changed, but certainly its cost can.
Euhm how is it in COH2, does the weapon drop?
I know the Squad sizes are bigger there, which could be an option to make them 4 man teams. Another option is to give them a more resilient armor type.
Because it's true that it's somewhat an issue that mortars are so vulnerable. Oth you can protect them by putting behind buildings or other shot blocking objects.
12ock
Zylfi17
Relic Entertainment
보드카 중대 
Heartless Jäger 
