the don't bother with bronze armor is highly subjective. If you have bronze, and trolls are scarce, you use bronze armor. If you have trolls, and bronze is scarce, you use troll armor.
Ive had both things in various maps over a number of characters. Most often, finding that many trolls is harder than finding that much copper and tin. Once in a while, you get more trolls, or even better, you trigger an early troll raid.