Wordy and Educated
Adam Smith wants you to pay attention to what he says. And if you were reading this book in the 1700s, the only way he was going to do that was if he showed you he was an educated man who knew what he was talking about. That's why he rarely loses any opportunity to write in a way that reminds you he's read a few fancy books in his time. Just read a sentence like this:
[This empire] has hitherto been, not an empire, but the project of an empire; not a gold mine, but the project of a gold mine; a project which has cost, which continues to cost, and which, if pursued in the same way as it has been hitherto, is likely to cost immense expence, without being likely to bring any profit; for the effects of the monopoly of the colony trade, it has been shewn; are, to the great body of the people, mere loss instead of profit. (5.3.15)
Whew. Hemingway he ain't. Even though Smith ended up selling a ton of books, his writing style shows that this wasn't his first priority. Neither was making his prose clear and poetic. His first priority was making sure people took his ideas seriously.