[RightDeve]

Yep, you're pretty much right there. It's always one of those myriads of SP's "little troubles" (IMO). But in the time being, what if you think it this way: a Mortar team (or an AT gun team; note that you can't bail out HMG's crews) is a single, fully working, integrated fighting entity, and they're trained as such. So if they left their mortar behind, they have ceased to become a fully working fighting entity. In this case, a "bailed out" mortar crew means they're so much "routed" or "scared to death" that they dared to cease as a fighting unit (mortar). Anyway, who wants to use crews as fighting units?

But again, your suggestion is quite realistic and real-life like; the rifles ain't stuck dead at the mortar gun, they're slung over each soldier's shoulder. But I'm afraid, there's a possibility that this application will render it gamey.