To be honest, it seems more trouble than it's worth to me. The forward firing arc of any given 'Mech is already a pretty generous 120 degrees, which can be increased to an effective 240 by torso twisting. Any "turret" that doesn't significantly add to that (in particular, that can't be pointed to the rear the way plain old arm-mounted weapons already can if you twist just right) can IMO safely remain a fluff element instead of eating up tonnage and slots.
I'd even go as far as to extend that argument to the original Jenner. So it had a "turret" that was easily disabled if hit? Well and good, but was that really a Turret (tm) in the game term sense of the word...or did the designers simply put all of its weapons into the same side torso and the Prototype quirk (+2 to critical hit rolls, significantly increasing the chance of both crits in general and multiple ones in particular) did the rest?