This idea has been merged into another idea. To comment or vote on this idea, please visit CORE-I-269 Activity Log default to a Blank Entry.
I primarily use the activity log to check the messaging system, and imagine many others do also. It would be handy if the default source was email, rather than having to manually select it each time.
I would recommend an ADMIN option to set the default. That way those that want to start with email can and those that want to start with API can.