Developing a Language Like Swahili

There's a certain point where words start getting so big that it's just simply not common. So I get the sense that the same is kind of true of these agglutinating languages, the natural languages like Swahili. You'll probably get a sense of what's acceptably long, what's common, and then what's just strange or just for special circumstances. If you can make a word that's a mile long, but you can't think of a reason that you would ever feel like using it, then why not cut that down to size a little bit?