There is no advantage to filtering in Google Analytics; in fact, that's a disadvantage because when you allow the bots to crawl your server you leave yourself open to DDoS attacks, which are now widespread and quite devastating.
You can look at the recent history of DDoS attacks across the Web here:http://www.digitalattackmap.com/
Some sites seem to be targeted more often than others. But the bots and the attacks have many different purposes. Most of this malicious activity is just automated stuff coming out of botnets that are trying to expand.
Most of the bots I see attacking my servers are coming from Web hosting companies. A lot of blogs using older software have been compromised and turned into spam/hacking proxies.