I'm not a super-brain on the subject of 'Why RAW', but I am a firm believer in it.
A. JPG files are 8 bit. Period. (or so I think, cause I can never save out a 16 bit JPG in Photoshop). RAW files are 12 bit, 14bit and probably 16 on some? RAW will allow you to have much truer colors, and many more colors. Losing the in-camera picture settings isn't much of a loss; in Aperture it's very easy to apply adjustments to one photo, and then 'Lift and Stamp Adjustments' to all the rest in the scene.
B. You can always degrade the quality later, you can't upgrade once it's set. RAW is as the camera sees it, no compression applied. With each edit and save you make on a JPG, the compression gets worse and worse. Why start out down 1 compression from the get go?
C. RAW files capture better detail in low-light situations, and post processing programs do a much better job of bringing out those details from a RAW file than from a JPG.
I'm sure there are more reasons, but those are some main ones for me. And I have no idea how accurate I am on the details, but it's what I've noticed over the last 4 years I've been shooting in RAW. If it's an important enough event then I'd not hesitate to go RAW. If it's just fun, casual shooting then shoot JPG. You can always shoot RAW+JPG and trash the RAW upon import if you didn't capture an image you'd really like to work up.
That's my midnight 2cents for ya. Cheers!