Hi Swathi,
As per Jurgen's comment above, certain fields like Basic Data 1, Basic Data 2 etc do not require Organizational Units. But if you try to select fields like Purchasing, Accounting etc, it will ask for Org unit there itself inside MM03/MM02.
Please let me know if you would like to make the Org unit entry as mandatory for Plant/Storage location.
Regards,
Akash