Were we to get everything we want when we want it, we would probably all grow up like cartoon character Richie Rich and have a tainted view of reality. But how can that be otherwise anymore? It certainly is not a level playing field by any means, there are those on the planet now that have choices galore and there are many more who face limited expression of self and can only dream of exercizing their will.
     If I could wave a magic wand, and have what I want appear before me, I would consider that the greatest thing, as would most people. This is the reality that those with loads of money face each day and probably delight in, for a while, until the novelty of it wears off and life becomes 'ordinary', albeit at a higher level.

     Those who can't get their dreams fulfilled live in a state of 'if only' and pine for the day their wishes come true.  Between their goals and the fulfillment of them is adversity, which can, depending on the level of difficulty faced, make the path forward arduous indeed. This we call drama, the battle between what is wanted and the forces that conspire to prevent us from getting there.

      Basically the plot line in most movies.
      So what good is adversity? Why is it so common?
      Is this a tainted world?!

     Can't tell you the answer to those questions but what I perceive from my own experience and the experiences of many others is that adversity might just be the best thing that ever came your way. It toughens you up, gets you to see things from a different point of view, shows you that things might not be configured the way you thought they were or worked the way they did, the list goes on and on. Adversity puts you in a different set of shoes and, walking those 'miles in the other person's moccasins', can't help but change the way your personal operating system works. Adversity takes, breaks, shakes, and quakes you. What emerges at the other end is a more humble person because through adversity you inevitably turn away from trying to power through life and see the value in trying to exert your will in a different way, perhaps even in cooperation with others!