Why is the turning chain in crochet patterns always a chain too long?

[YouWereRight]

Why do they always recommend, for example a 3 chain for a treble stitch when it always looks a bit baggy? Is there a reason when 2 chain would look neater?

It all depends on how you crochet TBH. Sometimes 3 is right, sometimes 2... just use whichever gives the right look :)