Into my opinion the battery is just right size. The battery is charged by the ICE and the charging range is between 40-60 %. There is enough room left in the battery for extra charging of braking and down hill driving. In the city you need to drive so that all accellarations are done by the ICE and then cruising by the battery. A bigger battery will be heavier and will increase the fuel consumption only.
RAV4 EV was not a bad car but was a failure because Toyota didn't really want to sell it like you said. It was made in Canada with Tesla Battery/Motors.And as I recall from the thread when we had a member who had one, Toyota only made them because of California's save-the-planet regulations and lost $10K on each one.
Problem is that you're still burning fuel, its just that it was converted to electricity. Whether its cheaper or not depends on your MPG and the cost of each KWH of electricity.My daily commute is 30 miles round trip. If I could get most of that in EV Mode, I'd be willing to plug in at night.
It would be cool getting gas every few months.