Something I have realised recently is there are people in IF who are embarrassed about its past. They almost don't want random passers by to see or be reminded of a Scott Adams game, etc.
I don't like this attitude, but I've also learned it's not like there's any kind of consensus amongst all the people interested in IF. If you want to consider the opposite position, visit Classic Adventure Game Solutions
(CASA) where you will find a community of folks who would rather play any old game than any new one.
Perhaps it's because there's the current quest to recommercialise IF (or 'monetise' it, to use the more vomity parlance constantly thrown at musicians like myself) that some exponents feel the need to draw strong lines between old and new. 'Hey, you wouldn't pay for those past games anymore, so here's something that is clearly not them (and therefore that you might pay for.)'
I.F. author Andrew Plotkin has just raised 18k+ dollars in about a week when he proposed folks pay him to get out of his dayjob and work fulltime on a brand new IF game for the iphone. And to also develop a platform by which future IF games could be delivered to handheld devices. A very impressive feat.