Hello Raghavendra
You can check the demo for usefulness of each module but in nutshell MDG offers -
1. Governance for Master data
2. Gives you integrated view of master data
3. Useful for planning
4. Faster communication and closing
5. Automation
6. Removes inconsistency and transparency
7. Can manage data in multiple system using hub model
8. Reduces cost and control
Once you go through all the documents, you will get more details about MDG.
Kiran