from your post here it seems you don't know much about star wars lore. The fact that the Hutts control several planets and operate many major hyperspace trade lanes make them more then just a minor player.
Yes by the time the Civil War comes around they are much smaller but we are not there yet.
Largest ''minor'' galactic power is quite an approriate expression
The Hutts are smaller than the Republic or the Empire, but much more poweful than Hapes or Csilla.