BIS is for one of a few things:
  • When content is brand new
  • When you want to plow through old content
  • When you don't want to go to the next expansion
  • When you want to do reclears for friends or for other folks
  • When you are a completionist and feel the need to complete it all
  • When you are free trial and this gear is the best you'll get for a long while
  • When you want to simply afk in Limsa to show off what you have accomplished