Because I do.
I tell people it's because of all the science and forensics and the witty reparte between the characters, but really it's because I like this dude:
I've been crushing on this guy (David Boreanaz) since his Buffy the Vampire Slayer days.
*sigh* I wait in anticipation for Wednesday nights when I can watch his handsome man-hunky mug on TV.
Oh and I have a teeny girl crush on his partner (Emily Deschanel) too:
I love win-win situations!