There are many benefits of linking your mobile number to an Aadhaar card. Also, it would help if you had it to avail of the different financial schemes such as government welfare programmes, invest in mutual funds, and get insurance.
You also need the Aadhaar card to be linked to your mobile number to verify your PAN card using the mobile number. However, the most important reason to link an Aadhaar card with a mobile number is to do the online verification of ITR with the one-time password that comes to your mobile phone.
Additionally, you can update your details in the Aadhaar card database using the one-time password sent to your mobile phone.
Lastly, you can now use the Aadhaar card for getting a SIM card from leading telecom providers in the country.
So you can see that there are many good reasons to link an Aadhaar card with a mobile number!