I get that importing raw materials for manufacturing is a great way to make money. I can also see why importing food might be necessary.
However, I also see trade routes for Rum, Weapons, Cigars, and other finished goods, often at a markup. Whhy would I spend money and trade routes on those things? Will Tropicans actually use them and, if so, what are the benefits?
To my understanding, Tropicans will use them and it will contribute to fun and food satisfaction (diversity of available products is a positive factor for fun and food quality).
You can also imports only to export later at a higher price (if you have good relations for instance). And sometimes you have to import something to fulfill a request, this is the main reason (if not the only) I found myself importing goods to be honest.
You never ever want to import finished goods aside from these 2 conditions.
Unless your map doesn't allow you to gather raw materials and it's required for a mission. For example, stealing a wonder and you want to complete it quickly.
You're so rich and your goal is to raise happiness for your Island to the highest level.
Otherwise finished goods are extremely expensive and can make you go broke quickly.
Your citizens will absolutely use some of the finished goods that can be sold in the Grocery or Shopping Mall.
If memory serves me correctly these are the finished goods that can be consumed:
Unsure about: Furniture, Jewelry, Clothes