It's probably an indicator of how deep the roots of software development run in me, that every time I create a 3D model in a modeling package, my brain almost immediately starts wandering off into the possibilities of wondering what recreating it programmatically would have offered me instead.
Instead of needing to implement some weird rigging or slicing regime to facilitate customization in my models with a 3D modeling package, I can do the customizations "on the fly" within my code, as needed. Need those wheels a little larger on later levels? How about a longer blade on that sword? With code, all of these customizations feel a lot more natural to me as they reside "just next to" the gaming logic that feeds them.
This, of course, is not the most pragmatic view to hold in the time-pressure-sensitive world of game construction. For most projects it tends to be a mix of models created in 3D modeling packages and models created via code. Sometimes the path of least effort (and pain...