It is the economics of how insurance plans are constructed.
roughly:
Premium=medical cost0%)+business cost(15%)+profit(5%)
The medical cost is minimized versus medical benefits by contracting with specific physicians/med groups for services at below market cost (usually a percentage). The base market cost of services in Ohio is different than the base cost of services in Massachusetts just like the cost of an apartment in the 2 places is different. Insurance networks are constructed locally not because regulations prevent them from being national, but because they HAVE to be local especially for HMO/PPO type plans.
The solution you are really looking for is for MA to stop requiring all the extra BS that people in the market may not want. Insurance is a contract between you and a company to provide the services YOU want at a price THEY want. If the government would get out of the way everything is possible if enough people want it.