Carelessness matters a great deal! The risks/damage to the security of the country are tied to the care of what and to whom things are revealed. Its the same reason Hillary should be tried, she was ignorant and careless w/ secure information.

Would you like to be specific about the damage?

for example blindly releasing/disclosing/leaking documents to the public can endanger in field operatives.

Vs a reporter should be smart enough to redact the sensitive bits and report in a general enough way as to not endanger any specific person (in the field).

I know it could. Can you come up with one single instance of that? Can you compare that instance with the Valery Plame leak and the leniency afforded to Scooter Libby? Any evidence Manning had control (and, therefore, responsibility) over the release?