They have been required for a long time, but Alex Shinn says:
I definitely think everything but the one and two depth combinations should be removed from (scheme base). Their use is generally a code smell. People should use destructuring, records, or SRFI-1 first..tenth accessors.
Ray Dillinger (Bear) adds:
The historic use of these entities was as accessors for structured aggregates implemented with cons cells. In a language that directly supports records, they have a reduced mission.