Is there a downside to encrypting too much data? If so, what?
I'm guessing things like
- too much data encrypted with the same key, possibly leaking information due to a collision
- encrypting non-essential data, wasting resources
could be a problem, but that's just a hunch, and that's not how we do cryptography.
On the other hand, failing to encrypt some data can leak some very sensitive information, and encrypting everything is an easy way to avoid that.