wilderness - 3:50 pm on Oct 2, 2010 (gmt 0)
Google and a variety of other SE's offer multiple user tools for different uses and devices.
Many of these IP ranges may simply result is "pesty" traffic (to be polite) as well as presenting a doorway for abuse for most webmasters.
You either accept the traffic (leaving open a doorway for abuse) or deny the IP ranges (and all the tools; closing the door).
Sure some innocents will fall by the wayside, however and generally speaking (IMO), not a large enough quantity to fret about.
Each webmaster must determine what is beneficial or detrimental to their own website (s).