can you please explain to me (or provide a link where it's explained) the benefits of using a 30 pin connector in comparison to a usb port? is it maybe so that apple can sell more adaptors? (i'm not sarcastic on this one, i'd really like to know)
There is an advantage to the user and to Apple.
The advantage to Apple is that they OWN the connector and will or won't grant other companies the right to include that connector into their products. So you'll never see a Microsoft or Android phone sporting Apple's connector.
The user can drop their iDevice into a bedside radio/clock or into a slot in their car dash and have their iDevice automatically integrated into that appliance or vehicle.
This means when you set an alarm on your iDevice, your bedside radio knows it and wakes you with music or alert through the larger radio speakers. Your iPhone GPS can become part of your car's navigation system, while your iPhone can become also become a hand's free phone using your car's sound system. Plus, you still have all your alarms, Address Book, and calendar available to you via voice command.
Life is good for you, and in Appleland prosperity reigns.