physics - 7:13 pm on Dec 14, 2005 (gmt 0)
One reason that I can think off the top of my head is simply they know they can not compete with Google or other search engines results at this current point.
Even if their search wasn't "as good" at least it would be something different. Plus they could use all that traffic data they collect to help their ranking algo.
Also, I'm aware that crawling and indexing are different things and the difficulty of creating an index ... still I think they should at least give it a college try.