One of my tutoring students wrote an amazing paragraph. She was writing a comp paper analyzing a short story, and pointed out a really brilliant interpretation of one section. It was well-written and insightful.
The trouble was, it didn't fit in her paper. At all. She was writing a paper analyzing symbolism with a strong thesis to match, and this piece, while very interesting, was a complete non sequitor. It was a blaring interuption in the middle of a well-organized paper.
So we put it on the "back burner" which is my shorthand for telling students, "You don't have to throw it out right now, but if you can't find a way to make it work, it will be easy to know what section needs to go."
Just because something is good doesn't mean it belongs.
It's another angle on "kill your darlings." I think we sometimes fail to acknowledge that those darlings are not only bits that we like, but are often objecively good. Damn good. Well-written, insightful, provocative, interesting, beautiful. It still might need to be revised out of your work. Just because it's a damn good piece of writing doesn't mean it belongs--in your English paper or in your novel.
We take a lot of things out of our novels during the revision provess--cliches, placeholder words, weak writing. The thing is, we often need to take good things out, as well. Well-written scenes that interupt the storyline. Fantastic, witty, well-rounded characters who just don't fit (and man, but they fight to stay in, don't they?). Beautiful description that, unfortunately, does nothing but bog down a section that needs to be pacey.
If it helps, don't delete it outright. This is what I do--I keep the damn good writing that has to go in a new, separate document. Call it the recycling bin. Or the back burner. It can always go back in if you find a way to make it work.