Why people keep bringing it up is because a lack of playoff experience, especially among goaltenders, is not something you want to bet the house on when your playing do or die hockey games. I can totally appreciate that some fans want to roll the dice and just see what happens. After all, just making it to the dance is a huge achievement, but if they have any plans on advancing a round or two, they will be contemplating bringing in another goaltender that has been down this road a time or two.
It just isn't obvious to me that "being a veteran" is one of the primary characteristics that predicts good play by a goalie in the playoffs. Are there any stats that show that the number of playoff games played in the past is a better predicator of post-season success than, say, regular season save percentage from the given year? If experience actually mattered, it should be very easy to prove it statistically.
Anecdotally, there are so many examples of young guys playing well and old guys playing poorly (and of course, good goaltenders simply playing well because they always play well) that I myself can't tell if experience vs inexperience really has any noticeable effect at all. Wasn't Stanley cup winning Fleury experienced but beyond awful last year? Wasn't Cam Ward great but inexperienced when he won?
Is it really the case that a team is worse off having an inexperienced-but-good-during-the-regular-season goalie (eg: Reimer) than an experienced-but-not-as-good-during-the-regular-season-goalie (eg: kipper with his .879 save percentage this year). Is it really worth paying the talent cost and acquiring the cap burden to get a guy like that? Until somebody shows me some clear evidence that inexperience in goalies makes a clear difference, I'm not going to give up those assets to trade for experience over demonstrated regular season skill. Of course, if an opposing GM just gifts us a great goaltender with little future cap burden then I'd happily take him.