We need two houses of the Parliament as Lok Sabha represents the people, it is directly elected by the people and exercises the real power on behalf of the people, whereas Rajya Sabha represents the federal structure, it represents the interests of various states and regions.
Both Houses plays positive role in matters of Legislations.
Second Chamber members are much different from Elected Member of Lok Sabha. Most of RS members are experts in their field, like businessmen, historians, journalist, actors, law expert, etc
The emergency situation when Lok Sabha is dissolved, only Rajya Sabha can take vital decisions in interest of nation and States.