I agree that the mindset of players needs to change. For instance, Shy typically hangs out in Har'Akir, and really only comes to Barovia when he is needed for a DM Plot or to RP with a Select few people. Shy and his main party typically hang out in Har'Akir, not because of the great spawns, or the excellent loot, but because we want to explore the area. A lot of people don't know this, but Har'Akir is a truly beautiful domain. Now some of you might say "But Doc, it's a flippin' desert wasteland!" And I'll say; "True, very true. However, when I found the oasis of Apep, I dropped a log in my pants." In addition, some of those old temples are simply beautiful in terms of architecture, and the server messages (The ones that describe what you're seeing) are extremely well thought-out and provokes the imagination.
This is an area that could very easily become a hub, and I have a habit of taking lower level good-aligned characters there just to train and explore the setting. You might be asking why I do this, and no, it's not to help low-levels powerlevel. It's so I can give them something to strive for. The most common comment I receive after one of these "Tours" is; "Wow, this place is amazing!" This is the sort of thing I want to encourage as a player, because as those lower level characters become stronger, they're going to want to go back there with their own parties, and explore all the places I didn't take them to. They'll take their lower level friends there, who will experience the same wonder I did when I first explored the domain. They in turn, will want to become stronger so they can explore that part of the setting, bringing their friends along, who will want to explore more of the setting, and so on and so forth.
The key to this is to not just show the lower level character everything the setting has to offer in one go. Give them a taste, the barest glimpse, and let their natural human hunger for exploration take hold. This is the key to getting people out of Vallaki.