The purpose of E85 is not to replace regular gas. E85 is simply another alternative fuel choice. I have not seen anyone claim that it is the solution to our energy problems, it is just one more step in the process of finding new fuels.
Flex fuel vehicles do not cost more than regular vehicles. I have never seen a manufacturer charge for the option (and there are a couple flex fuel vehicles in the family, so I should know). Fuel filters do cost more because production of E85 capable filters is lower, but they do not amount to much in the overall cost of maintaining the vehicle. Other non-maintenence parts of the fuel system (lines, injectors, etc...) are expensive in all new cars regardless of if they have flex fuel capability or not. According to the owner's manual for my parent's flex fuel Ranger, using E85 is actually better for the longevity of a fuel system designed to use it anyway.
My parents have been filling their flex fuel Ranger with E85 since they got it in their area. The truck does get slightly worse fuel economy, but that is the price we currently have to pay to use a cleaner burning, US produced, better performing fuel. You give some to get some. For my parents the trade off is worth it, and their Ranger will continue to be fueled with E85 as long as it is available, like it or not.
If you do not like E85, don't use it. It is that simple. All production Flex Fuel vehicles can run on plain gas too. The Ranger mentioned above did for over four years because no E85 was available locally. I personally like the idea of having a cleaner burning, domestically produced, high octane fuel though. I wish my truck had flex fuel capability.