I use the modeller all the time. Not for anything fancy but I often dissect ready mades and bang them together into another model. Also for simple vertex shapes for masks and anything glows sources. Taking the modeller out would be a pain in the backside and could only be suggested by someone who doesn't use carrara often enough ;) 

just a small dig :)

 

a knife tool would be invaluable in the modeller and its really hobbles the usefulness of the vm for me. Knife tool is you draw the cursor across some edges or a poly and where it cross the edges it makes a verticie and if it goes from one edge to another in a poly it makes a new edge - all the way  through the mesh or just on a selcted polygon, great for cuitting loops in etc when box modelling especially