why were some people against Mandal Commission's recomodation
Answers
Mandal commission recommended for 27% reservation in jobs in government and public sector. Also an age relaxation of 5 to 10 years was to be given to those classes. It was in 1980. Mandal commission submitted its report to the then President Sri N Sanjiva Reddy.
Prime Minister VP Singh announced the complete implementation of Mandal commission's recommendations as an order (ordinance) in 1990. It created a lot of stir among people of forward castes and other castes. Suddenly they would lose jobs available to them. Many unemployed were not in OBC but they were not economically or socially well off. So reservations were a big hurdle for them.
A caste can not be used as a parameter to truly define backwardness. It should be only economic status that should be used for backwardness. As in 21st century castes do not really matter in many social issues or for social status.
Using caste as backwardness is not appropriate. Using caste for reservation results in unfair treatment of other castes. Also the performance of government and public sectors will suffer badly. Also using caste for reservations is against the promise of equality to everyone - as mentioned in the constitution.