Immobilizer is the need in car now a days, no one insures car after 5 years, or if they do they waste lot of money for security reason as accident are rare to happen and you can give money from your pocket until car is totaled but its not every year scene.
Another thing is that you do not want your car to be picked up in minutes by regular chabi maker or underage boys doing car theft for minimum amount and handing over to the bigger mafia, with immobilizer it is much secure, now one can park his car and not to rely on insurance only.