[Aloha]

No, thats not it at all.

Analog reproduction is far less complex and easier to explain in pictures to an unknown entity that might find it. Figure that they'll need to build what effectively amounts to a record player to play the thing back. In addition there was no digital technology of the time with a large enough capacity to store what we sent, or that was durable enough to deal with an unknown time in space.

Quality of the reproduction is not a consideration.