Yeah but it can also be used on airfields, which they DID use it on, not specifically... it killed hangars, planes, rnwy...speaking of which, we need craters that damage planes trying to lift off. and yes, it is vulnerable, but when used in multiples and with AA like the whirble. Along with having it away from the spawn and probable path to town/base, u got a threat that needs to b found and taken out, if left alone, the town (and Gvs in town) can be flattened. You can use it to flush nme GVs out also, a 155mm landing next to you can easily track and turret a weaker tank, (let alone hiding M3s and light vehicles). On a base, you sometimes have multiple GVs stationary around the VH (mainly flaks) that can be hit by artie and destroyed...
Modify: if u have a SP Priest or a German SP Hummel, this can be easily done (with the protection it needs, or hide it)