Law of DMU is important in practice.

Yes, I agree with this statement.

i. The law of DMU helps consumers in deriving the maximum satisfaction from the given income level.
ii. It also helps Producers in determining the price and sale policy and thereby maximising the profit.
iii. It is helpful to the monopolist to practise price discrimination.
iv. It helps government in implementing economic policies. It is helpful to financial minister in framing various tax policies.