If we don't edit the questions, the destruction of a bad tag would be delayed, and then people would keep using useless tags. That's not to say that editors should just rip through all questions with a given tag, mindlessly removing it from them. Rather, every user who retags a question (or makes any minor change to any post, really) should also make sure that there are no other obvious problems.
If the question's grammar is a shambles, please rewrite the text so that the actual question is understandable. If there are small capitalization or English syntax errors, please fix them; it really doesn't take too long once you get a little practice. If you can't repair a question or don't want to, please pass over it so the next retagger can handle it. When you find an edit in the Suggested Edits queue that only adjusts the tags while leaving obvious problems, reject it, either with a custom message or with the "no improvement whatsoever" one.
Of course, a question can be a shining example of quality prose while also being a poor question. If it can't be fixed to obey the help center's guidance, it should be downvoted and/or closed with the appropriate reason. Questions that are downvoted, closed, or both are likely to be automatically deletedautomatically deleted.
Finally, if old bumped questions bother you, you can always browse a different questions list, like the one of newest questions (by original post date).