Quoting the Origional Message "reminds" the reader of the previous conversation..., and definitely helps the reader understand "what" you are responding to!  Very often you will send mail to someone, and when they respond you can't remember what the original conversation was all about!

Yes..., it is a "very good" feature.

BUT..., You must tell Netscape you want to Automatically "Quote" the original message you are responding to.

Select the Composition Tab..., this Window will appear.

"Click-on" the Check Box...,  Automatically quote original message when replying  

("click again" to Un-check the box)

Netscape is now "set" to Automatically Quote all your messages that you Reply To: