Editing tags is not adding any information to a question/answers, it is a mainly organizational task. It is not an interesting activity for most users.

It should be possible to see questions sorted based on the time that last significant activity is performed on them. And in place of stating who has performed last activity on the question, it should say who has performed the last significant activity on them.

The main example of insignificant/uninteresting activity is tag edits, but small edits to questions/answers (like spelling corrections) might also be considered insignificant and uninteresting.

I have posted it on SO meta:

http://meta.stackoverflow.com/questions/69659/a-page-for-questions-sorted-based-on-last-significant-modification-not-tag-edits