Hi, David.  Welcome to the modeling forum!

Simply put, there is definitely a need for knowing how to polygon model objects, using traditional sub-d and box or edge modeling techniques.  Why would you wish to create a simple table, for example, in a sculpting application, when you can model one very simply and efficiently from a box in any 3d modeling package?  When it comes to quickly creating most hard-surface objects with good topology, poly-modeling is still much easier than virtual clay sculpting.  Even some organic shapes can be faster to achieve using subdivision modeling from standard polygons.

Sculpting from virtual clay definitely has it's advantages, and with the awesome retopology tools available now in packages like Zbrush, 3DCoat, and even the native tools in some general 3D applications, it's becoming a standard method to achieving complex organic or semi-organic results very quickly.  To say it isn't worth it to learn to model, however, is not being logical.  Retopology, or should I say, good retopology, will require some knowledge of how edge flow and polygon placement affects smoothing, subdivision, and UV's.  The  best way to understand this is to learn how to model in polygons to begin with.

PS:  I noticed your first post to the galleries here is actually a render containing one of my freebie models.  Thank you for mentioning it in your description, by the way!  Just so you know, that particular chair model was created entirely with Sub-D modeling techniques in just a few hours..  I think if I were to create the same model by sculpting it first, then retopologizing, it probably would have taken a bit longer.  Also, be aware that detailing models in applications like Mudbox, do require a quad topology to begin with.  Again, this comes from a basic knowledge of how to model things "the old fashioned way" first.  Not sure everyone would agree, but I'd be eager to hear from those with an opposing view.

Hope you keep posting to this forum.  It needs more activity. ;)

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