There are many people who would like to run tor exits but whom don't because of the inevitable flood of abuse complaints.
At the same time, there are a great many high traffic destinations on the internet which have little to no complaint potential because they are effectively read-only or are otherwise understood to be tor/anonymity friendly. Examples include most news sites, virtually all CDN services (used to distribute images by large sites), freenode IRC, Wikipedia, other anonymity services, search engines, and probably most instant messaging networks (?). Right now nodes can attempt to exit to only to safe locations and protocols by carefully crafting their exit policies but this takes a fair amount of work to maintain, clutters up the directories, and risks making the exit look like a single-purpose-password-sniffer. How awful would it be to create a community managed list of 'safe destinations' distributed by the directory servers as a single object which exit operators could include in in their exit policies and further refine with local rules? Some exit operators would likely switch to safe-mode, reducing the total amount of universal-exit capacity but if the safe list included enough high traffic sites it would probably more than offset the loss and arguably anyone who switched was likely to quit in any case.
