Perhaps it's just the industries I've worked in, which tend to be highly regulated, but I have such a hard time seeing why this idea isn't more intuitive to people. Every single scrap of sensitive information you have laying around is something that has the potential to fuel a very expensive, possibly even existential, crisis for your company.
Even for the non-sensitive stuff, keeping it around "just in case" increases the risk that somebody who has taken a couple classes in how to use R or Pandas and is still a bit starry-eyed about Big Data starts making questionable business decisions based on unskeptical interpretations of biased results drawn from convenience-sampled data of uncertain provenance.
The default shouldn't be collecting and warehousing everything, the default should be, "when in doubt, throw it out."