Not storing passwords in plaintext is good in theory, but in practice it’s not always possible.
For example, a mail server must be able to access plaintext passwords because the APOP and CRAM-MD5 authentication methods require the server and client to compute hashes based on a salt provided in the session.
TLS solves this, but TLS isn’t always possible.
I’m sure there are more authentication schemes in the world that use the same principles. Until they go away, plaintext passwords won’t either because plaintext is better then the alternative.