Why is it advised to use the pre-printed forms?

The benefits of pre-printed forms are

Time saving
No data mismatch between online registration & on the form
Since all the dtls are printed, no question of missing details
Client need not search & update ISIN / MICR / IFSC codes etc.
Even partner / advisor / branch can apply for SIP on clients behalf and directly download the form and send it to client for his signature
Even if the form is lost, new form can be readily downloaded