A friend sent me a link to these old Alan Moore interviews about comics, and one of the points Moore makes is that comics are as good as or better than other art forms due to their accessibility. I haven't finished the series yet, but I would wager that another argument put forth in comic's favor, if not by Moore, than by others, is that comics have a greater cultural impact than other art forms. 

This is all true. But, if people want to use this as a metric for quantifying "quality" for any given media, then get ready to move over for the art that completely dominates the field when it comes to this sort of thing, that being corporate logo design. The accessibility and cultural impact of corporate logos dwarfs any art ever made. If comics, a medium that constantly struggles for intellectual legitimacy, wants to share a bed in a semantic crawl-space with Nike and Disney, then I guess more power to them, but it's not going to bring anyone any closer to the kind of legitimacy that traditional literature or film has. 

As always, comments negative or positive welcome.