Firechaser Express is a perfect example. An attraction like this in Orlando almost certainly would need to be themed around an existing property like Chicago Fire, Backdraft, or something else. At Dollywood, they can come up with a generic theme, put some elements on the train and station, and that's it. Intellectual property rights alone cost Disney and Universal billions (IOA reportedly spent $1 billion for the rights to Harry Potter). $300 million would build one big attraction in Orlando, but at a place like Dollywood, that can build dozens of attractions (even the huge and costly Wild Eagle only had a $20 million price tag).
Resorts are surprisingly inexpensive investments to build, but can be difficult and expensive to maintain. It requires employing an entirely differently-trained staff from standard theme park staff (something Universal understood when they subcontracted their resorts to Loews). The Smokey Mountains are already an extremely popular tourist destination (without Dollywood), so it makes sense that the resort will be able to make money year round even if guests are not spending all of their time in Dollywood.
This is a great sign for smaller theme parks, and perhaps will demonstrate to others (Busch Gardens Williamsburg and Tampa come immediately to mind) that having your own resort can inrease revenue.
When I went to DLR, I stayed at The Grand Californian. The Universal Loew's hotels are great (Portofino FTW), and any of the moderate+ hotels at WDW are nice.
As for Busch Gardens Tampa, if you've never been, you should be aware that it is a beautiful and exciting park - in the middle of the ghetto. Sorry to say, but I remember being slightly scared while only a mile from the park, thinking I'd made a wrong turn somewhere. I would love to see some of the run down slum purchased, torn down, and made into a family-friendly on-site resort, but I seriously doubt that has any chance of happening.
I don't know anything about Williamsburg, but I'd love to visit that whole area!
Anyway, good for Dollywood! For Universal or Disney, $300m may not be much. But it definitely is a huge deal for a small park like Dollywood and they deserve tons of kudos!