This "vast majority" to which you refer was happy with their insurance plan because they never needed to file for a large claim.  Before the ACA, some insurers standard procedure was to deny every single claim, payment was dependant upon a successful appeal to the denial. 

Whole offices specialized in underwriting, sifting through the fine print to find any reason to deny coverage. I know some people who won bonus vacations to Hawaii for doing this nefarious job.

Sure happy customers paid a reasonable premium, but when momma got cancer, or her lumbago flared up the insurance company left the long standing customer standing with a bill that led to bankruptcy.