Prior to getting my Prius I had a Civic, but Fi had a Xterra. We traded in the Xterra for the Prius and it was the best decision.
My insurance did not increase. It is the same as the Civic was and the Civic is a 99 and the Prius is an 08. I am not sure how that worked, but I was happy.
Also, the oil changes are not more expensive, you just have to get them at the Toyota dealership as they have all of the parts for the Prius.
As far as repairs - the new toyota hybrids come with a 7 year electrical part warranty and a 5 year powertrain warranty. So if anything happens to the battery, which is very unlikely, it is covered for the first 7 years. Because the Prius has been out for over 5 years you can look at the history of issues with the batteries and there really have not been many.
I am so happy with my Prius, I love it!!
However, I agree that if I had a Civic or something small that got good gas milage I would not trade it in for a new car if it was working fine. However, if I was in the market for a new car I would look at a Hybrid. Also, you can still get a tax credit on many hybrids (just not Toyotas).