As a matter of courtesy and respect as well as for the sake of reinforcing the sense of COMMUNITY on HupPages, I consider it a responsibility as well as a privilege to respond to others' comments. Pragmatically, it also helps to "flesh out" who you are as a writer to others who may just be browsing through the comments section. Who knows? Just by responding to others, you may very well be setting out a WELCOME MAT for both HubPages veterans and newbies to check out your Hubs.
At the end of the day, it's all good!