One of the remarkably common user errors with pg_restore is users leaving off the -d option. (We get cases of it regularly on the IRC channel, including one just now which prompted me to finally propose this)
I propose we add a new option: --convert-to-text or some such name, and then make pg_restore throw a usage error if neither -d nor the new option is given.
(Yes, it will break the scripts of anyone who is currently scripting pg_restore to output SQL text. How many people do that?)