Apps, I feel will lower the resale price of the car. Facebook and Twitter today is like buying a 5 year old car and see LiveJournal and MySpace.
Things change, and tying into special products is asking for obsoletion, whether it's iPod/iPhone holders and software, Facebook/Twitter tie-ins or other proprietary tie-ins.
Generic Bluetooth, on the other hand, is a plus. That's an open standard, and will continue to work, and future devices will be backwards compatible with it.