OK, pardon my being dense...I want to make sure I understand the process.

After getting the card, meeting spending threshold and receiving the miles, I would do the following:

1) buy a refundable ticket for more than $450

2) choose the option to pay with miles (using up the bonus miles I was just given)

3) cancel the ticket after issue, request a refund

4) instead of just crediting back the miles, Delta will send me an Ecert with a value of $450 which I can apply towards future travel without using the 'pay with miles' option

Why would Delta issue an Ecert with monetary value instead of just crediting me back the miles?