Possibly been said, but organic objects should not be built in seperate parts, having an arm as a seperate object, not attached to the body looks terrible, even covering up the nasty seam, or lack of would look tacky, not all characters in all games wear shoulder pads.
Hence why building sets are good for this type of modelling practice, the ability to mix and match a different building works perfectly when trying to create a varied level, or scene. At the end of the day though, it will still require creativity and certainly won't look unique. One thing that bugs me the most is that a lot of people overlook a consistent colour scheme in their artwork. Any building set, or free media like this would still have to be edited within a 3d package and it probably would have been easier to create it from scratch yourself.
The possibility of welding the seams together internally would work, but the animation, textures and topology would most likely suffer for it, however good your algorithm is, it's not going to be as good as if you do it by hand.
That being said i can see what you are going for, but at the end of the day it's much easier to just create it all in one. The topology can only work better this way. Call me a cynic but people should just learn to model,.
However good your game mechanics are, placeholder/free models are still never going to stand out, even in the indie community. People are just looking for a quick fix, some free models they can slap onto an existing engine and call it their own.
