Shorts are also useful when you have private information the market doesn't have, yet. (As opposed to bad news the market already knows but chooses to ignore.)
Ie: dig up dirt on a company, short their stock, publish bad news, close out your short position.
Who wants to go long a company (ie invest in equity), should welcome the ability of others to short: it ensures you can buy for a fair price and that there's a smaller likelihood of skeletons hidden in their basement.
