Should we retag and reopen old open-ended questions that are closed?

There's many old/historical questions on Stack Overflow that were off-topic when asked.Now that we have sanctioned previously off-topic categories and thus have tags as tooling-recommendations and best-practices, is it appropriate to retag those questions and reopen them?

As a matter of fact, you wouldn't be able to close such a question today, because the "Primarily Opinion-Based" close reason is disabled.

Example: Daylight saving time and time zone best practices. This one has already been retagged, but not yet reopened. Should it have been retagged? Should it be reopened?