We are currently weighing whether to enable the IAB bot filtering functionality in Analytics (this is a communication challenge internally - as a B2B media company, we often quote traffic numbers in sales materials, and these numbers will obviously be impacted).
Some of the primary downsides of enabling IAB filtering functionality include:
no solid estimate of how enabling filter will impact traffic numbers
loss of the ability to accurately measure year-over-year growth
If a segment were available in Analytics that allowed us to either exclude or isolate bots, we'd be able to address both of the above concerns. The segment would obviously need to be regularly updated to keep up to date with the IAB list.