> Instead of one system, you need two.
That's a common refrain, but in my personal experience I don't think it really holds water because of the additional savings you get:
1. The battery can be much, much smaller. This results in huge savings in cost, weight and environmental impact that offsets a lot of the cost of needing a gas engine.
2. You will end up utilizing much more of the battery. That is, the only reason you need a big battery in EVs in the first place is those thoughts of "what about longer trips", even if you only take longer trips 3% of the time. Plus, I would frequently drive my Volt's EV charge to near zero or zero (but still only use something like 0.1 gallons of gas), but with my current EV I never take it below ~30 miles of charge for fear of getting stranded.
Your other examples don't really hold for plug-in hybrid vehicles. I think the big reason they were largely passed over in the marketplace is they were often "bolted on" to existing ICE models, so people saw them as just an additional expense with marginal benefit. Perhaps a good marketing guru will market them instead as "All the best parts of an EV, but with all the things that you hate/that scare you are fixed!"