Several of the actors and production people on TVD have mentioned DS in interviews, but this is probably the first time that anyone other than Kevin Williamson has basically admitted they're a fan. (And as we saw in the article that I posted a link to last season that did a side by side comparison of the two shows:
Dark Shadows and The Vampire Diaries
DS and TVD do actually have a lot in common.)
As for some people being dismissive of DS, while it can/does factor into things, it's not just that it's an older story - after all,
Dracula doesn't get dismissed simply because it's older. It's more so that DS is a soap, and while things have improved somewhat over the years, soaps still get dismissed out of hand. Though it's mostly by people who've never actually watch them.