Not sure if you're trying to pad your post count, or just replying with incomplete knowledge.

By quoting, I am verifying that this is the original unedited message, to prevent a hacker from editing the message which his own address and signature.   
Since I have quoted it, even if it is edited, anybody can look at the text within my quote and verify it themselves.

This is the exact same reason Gavin's testimony about Craig Wright's signature being true was not worth listening to. Signing is supposed to mean that you don't take anybody's word and verify it yourself. You should not take my word that the signature is right, and verify it yourself. By quoting, my job is not to ensure that the signature is correct, but just that the signature has not been changed since it was posted.