Why not? Because all the cities you listed are fairly near the coasts. Branson is much more central and would be a much better driving destination than any of the cities you listed. And it really is a family place. Their business really picked up after 9/11 when people were avoiding flights. I think the weather is the biggest reason Branson would not work, not the town itself. Although their would need to be major changes to the road systems. It is hot, humid, and buggy in the summer, and nasty and icey in the winter. Not to mention all those hills. Hmmm... maybe they should build in CO instead, lol! We have more sunny days than any other state, and it is rarely too hot or too cold.
I've lived near your neck of the woods (Southern NH), and love the city of Boston (ONLY large city I like, btw) but there is a massive difference between the midwest or south vs the east coast. TX would be ok if it wasn't for the heat, but if they ever built in the North East, they would have to ship all their cast members from other areas of the country, or they would loose their reputation quickly!