Hmm... I was under the impression that something like star trek disruptors or phased arrays would actually have better and faster coverage than a turret. While I'm not all too familiar with how beam weapons work in star trek, I did do a bit of digging into phased arrays as an actual concept since I too like the idea of going turretless in some cases. Any way, from what I remember, you'd likely have faster target tracking and an increased ability to hit faster moving targets with bigger weapons because there is no turret assembly to lug around to track a target with weapon barrels, but conversely, the actual weapon would likely be a bit more likely to be destroyed if hit due to the lack of an armored casing. Of course, you could counter that with simply adding armored covers that slide out of the way so you could shoot.
As for immersion, they technically could still aim for your "turret," its just that it won't actually be a turret so I doubt that it would do much to ruin peoples immersion if that route was taken... I mean look at star trek... You don't see many turrets there unless you go JJVerse, and people seem to like it just fine.
