After a consensus was reached in this post, the design tag was burninated. Since that time, I've seen it recreated a few times by different users (those that didn't know about this tag's history). It was removed and eventually burninated again each time, without any responses from those users.
However, users coming with off-topic design questions can still create this tag without seeing the feedback that's shown when trying to create a blacklisted tag. I think that this tag should finally be blacklisted so that users can become aware that questions solely about design don't belong here. Sure, it's not the only problematic tag we've had, but architecture and pseuodcode questions seem to come up rarely.
Be aware that this is not similar to the design-patterns tag. It is used with questions with complete code that follow some design pattern, which is on-topic. On the other hand, questions with the design tag usually have incomplete code, as the focus is on the current approached design, not on the code itself.