Nice conversions there! Lovely going with the army so far.
The trade-off between pre-posed models and multipart kits allowing maximum creative freedom when building goes back a long way, longer than most here have been into the hobby. More in detail here, but the short version is that preposed models as seen with classic metal miniatures allow the sculptors greater creative freedom, whilst multipart plastics with dodgy naturalistic posing but great varieties on hand to build them however you like (as exemplified by early 2000s plastics in particular) allow the hobbyist greater creative freedom.
The move back to preposed miniatures in plastic is all about recapturing some of the quality and better poses lost when previously transitioning from metal to multipart plastic. This swing of the pendulum comes at the expense of Lego-like customizability, and a loss of fun when building kits.
Both opposing ends of the spectrum have strong virtues going for them. It remains to be seen if a perfect balance between freewheeling convertibility and quality posing can ever be reached for future plastic kits.