Trading can either be about money or about RP imo.
Though most times you will need someone to RP with, in the second option.
It's great having to do some RP trading, like some factions transporting huge amounts of food or other stuff to Crete. But that rarely happens with other factions than the corsairs it seems.
And that's when trading factions become uninteresting imo. As a Miner I know what to do, I somehow like sitting around at one point with the constant threat of someone coming there to pirate me. When trading I don't like flying around so much - especially in house space with all those huge systems were you have to rely on trade lanes. I did some trading on my Zoner Guard in the Omegas, Omicrons and sometimes even Taus or Sigmas...but that's different than being in a house-trading-faction.