Why solid models?

I’m trying to do this model for a game, I’ve looked a some models that other persons have made, and they always try to make each object on the model solid, no holes anywhere…
Is there any advantage too make the models like this, imo it just creates more faces, wich is a bad thing i guess? The model still looks the same from the outside…

Picture on a none solid model:
http://xs220.xs.to/xs220/07414/NotFilled.png.xs.jpg

Solid model:
http://xs220.xs.to/xs220/07414/Filled.png.xs.jpg

Not exactly the ideal pictures since the second picture ain’t actually solid (pretend it is), but I hope that you get what I mean.

Thanks!

I could be wrong but I think the main reason to use solid models it that it is slightly easier to UV unwrap.

as long as its one object i don’t see how there would be an issue if you make the bottom verts flush with the plane. like nyrath said its probably because you can get details of a uv map in the seam between the cylinder and the plane without an annoying shop job. personally i do things your way. its lazyer and faster. and yields the same result. so if theres a reason other then uv i want to know to

One reason for that is the limitations of Z-Buffer accuracy. If you make models from parts that overlap you’ll end up having nasty flickering at certain distances. And then there’s the thing that some modern engines no longer think of things as triangles, but use polygon strips instead(and that requires continuous surface to work).