I have a "smart" phone that has internet, GPS, and map data, and an SD card filled with music. Why can't I piggyback off my phone? My phone is designed with touch interfaces in mind, just like modern cars. However, two years from now, I can replace my phone with one twice as powerful, faster, and more features... and i'll be stuck with a car that uses slower, more outdated technology. This is similar to television sets becoming computers.. except computers that are locked in time and are only as good as when they were last updated.
I should be able to plug in my phone and either use my phone's interface (or even a custom app from the carmaker) to do whatever I need to do, pull up anything I need, etc. This way, I won't have to hack up my dash to put an ipad in there.