It'd be beneficial, because simply put it would make it easier for people to know when new comics are released. There are plenty of applications for computers, smartphones and other devices that use the RSS feature to keep track of websites. Plus by adding a subscription service like that, it'll be registered on google and will get a larger audience of readers (as in people) to view the wonderful comics. Google Reader in particular has recommendations and will suggest other comics to people based on what they're already subscribed to. If it sees people with maybe 20+ webcomics on their list of subscriptions, then it's highly likely it'll pop up.
Just an idea, but I think it's a good and convenient one nonetheless.