Packaging for new cards

Is there a reason the envelope and the slip on paper is the size it is for new cards ?

Just seems a waste when the card is less than half the width of the envelope.

Better than them just sticking a label on the card and throwing it in the mail.

All other banks in the uk normally send it on full A4 making Monzo the smallest.
The packaging is there to greet new customers and keep your details safe inside