Chaucer chooses to group these five tradesmen – a hat and accessories dealer (Haberdasher), carpenter, weaver (Webbe), cloth-dyer, and rug/tapestry maker (Tapycer), respectively – together in one portrait. Why? Maybe because with them, he's actually representing just one thing: the upwardly mobile tradesmen who, by forming guilds, or trade unions, were gaining a lot of new power and money for themselves during this time period.
As part of the new social class (and money) that was forming in the cities and towns in the late fourteenth century, the tradesmen's skill and affluence is visible in the fine quality and workmanship of their belts, pouches, and knives made not of brass, but silver. So fine and prosperous are these men that they are worthy not only to lead in the guildhalls, but also to serve as aldermen, or leaders of the city. This last position is something the tradesmen's wives regard as merely their due. And the wives, moreover, very much enjoy their newfound affluence, liking to be called "madame" as a gesture of respect, and to parade in front of the rest of the church congregation in a fine gown carried by one's servant.
With the Tradesmen's portrait we have a similar situation to that of a merchant – "new" money coming into its own. What's interesting is that we get the feeling that the wives of these tradesmen can be somewhat difficult, just like the Merchant's. By making difficult wives an important component of both the Merchant's and Tradesmen's situations, Chaucer could be commenting upon how these new ways of making money are changing the relationship between husbands and wives, too.