they originally separated the wifi access point and ADHOC, for fears of easy breaking into a pc.
I like it like this, as Windows is still too hackable.
Imagine people in the metrorail, with their advanced phones, netbooks, laptops, continuously being probed for information through a direct network. For the user it's often hard to see when you're connected to a network, or to a network via another computer.
That other computer is connected to you via an ADHOC network, and technically could find ways to get private information from you.