I think it is very important to have Work-Ex before doing an MBA....
-- There is a shortage of Good Managers in India
-- MBA teaches you about all the different aspects of business and you are expected to implement it in your Job
-- With out Work-Ex everything is theory, you are not able to relate to it and get advantage of the knowledge that is imparted in the classrooms.
-- Any employer will prefer a full baked cookie then a half baked cookie. Think of the Salary you can negotiate with Work-Ex against without Work-Ex and make a choice :)