Not necesarily. If the hull can already house 7 dismounts (which I´m damn convinced off given what we saw during the parade), then there is a case for using part of the hull for a different capability. Now, why mount them in the hull instead of the turret?
1- Allows using bigger, heavier missiles and in greater quantities than what could be mounted on the turret. The turret remains more compact and lighter.
2- Since the missiles would fire vertically, they don´t need to be pointed physically towards a target by a turret-like thing nor a proper turret.
I think these reasons may be good enough for using this very non conventional design (if thats indeed whats going on). Not what I would have done perhaps, but it makes a lot of sense.