I've heard it said many times it's much easier to make your audience cry than laugh.
I'll add to that that it's easier to make your reader identify with falling in love than say, having your arm ripped off.
When we write we appeal to common experiences to allow our readers to fill in the blanks. The nervous tingling of your spine when you make eye contact with that guy/gal, the lingering burning sensation on your skin after you "accidentally" brush hands. These are all things we can allude to without going into detail. They know the drill.
If, though, we're talking about having your spine ripped out or a literal burning of the epidermis we tend to fall back on stock phrases. How many times have you read about "searing pain" or "explosions of pain?" It's like we can't even write about pain without using the word itself.
Even better is when the tortured character loses consciousness, the end-all writer's escape. C'mon? Really?
I don't have the answers about how to write pain effectively. I can say my approach is to read. A lot. And I pay attention when someone has written something distinctive enough to make me writhe a bit.
Writhe.
There's a good word.