Well, that is an option with the understanding that it puts the burden on the states exclusively. 50 insurance markets with 50 different regulation systems. Grossly inefficient however, a model that needs to be retained as some insurance companies only want to compete within a limited geographic area.
Under my recommendation, insurance firms could opt to comply with the national classification system and sell to the entire nation OR they could continue, as you pointed out, to selectively choose to compete under 50 different state regulations.
I am of the opinion that by having a national market, insurance companies can compete nationally and there by, become more efficient, as competition will improve the options to the consumer and prices will be contained.
Let's take a step back and make sure we understand one of the primary flaws of ObamaCare: It was a Federal law that forced everyone in the U.S. to pay New York, D.C. and Los Angeles prices for their insurance coverage even if they lived in Mississippi or Arkansas or North Dakota. This is why the insurance industry absolutely loves ObamaCare, and will love RyanCare even more.