The rationale was that laws governing health insurance should not be set nationwide by the state with the loosest regulation.  Alaska should be allowed to set laws governing health in Alaska.

The fear was that if health insurance companies could sell plans across state lines, we would end up with the equivalent to corporate law where so many companies are registered in Delaware because of Delaware's tax and disclosure laws. 

With federal subsidies on the ACA marketplace essentially setting a standardized nationwide floor for coverage, I imagine that discussion could be re-opened.