You're entitled to your own opinon. But for my time watching cricket, the world cups have easily been the most prestigious prize in cricket. When you hear anyone who has won it, talk about his most memorable moment in cricket, its ALWAYS the world cup.
You're right. Something IMO needs to be done with test cricket. People in Asia, which is main source of crickets income, are just drifting away from the longer version of the game. The crowds all around the world in test cricket have been poor. Giving the ranking more importance is one way. Maybe bar the top 6 or 7 from playing the rest(Bangla etc). Then each team having a similar schedule over the 5 year period(which is already in place i think), and points awarded on the basis of results, which is also there but not given importance. Make it clear to the public, and make it easy to understand, how points are awarded. And then maybe every 3 or 5 years, each of these top teams having played each other the same number of times, a champion is decided, like in a football league. And then you start from scratch, or as they have it, it continues on.