Another advantage is that the loan is processed sooner and requires minimal papers work. Since banks have your details. The amount of loan approved depends on factors such as average balance in your savings account and the time duration for which you have been a customer of the bank.
Many a times pre-approved loans also come with a processing fee waiver. Of course this varies from bank to bank. Some banks charge a processing fee, but would refund the same once the loan is availed.