You could always ask if the manager will allow it, but the policy changed well over a year ago. (Maybe two years ago?)
I was told by one store manager it was because some customers would save all their expired Kohl's Cash to use around the holidays, when all the big sales were on. I'm sure that hit Kohl's bottom line.
Also, they used to allow you to return something that earned Kohl's Cash for a store credit (during the current event). They stopped that because shoppers would buy something, return it for a credit during the promotion and then use it to buy something else and get more Kohl's Cash on it. Shoppers were buying big ticket items like Dyson's, earning $90 Cash and then returning the item.
You can see how some people abusing the generous policies ruined it for every other honest customer. There's always someone willing to "play the system". 
"" A little learning is a dangerous thing."-Alexander Pope