While insider trading and short-selling are largely strictly regulated and, on the face of it, discouraged, in most markets, there is an academic argument in favour of the two practices.
From The Telegraph:
At first blush the argument in favour of insider dealing was seductive. An insider who bought or sold shares had intimate knowledge of the company’s financial performance. Armed with this knowledge, he was best placed to assess the true value of the share, so where the share was undervalued or overvalued an insider’s intervention ensured a correction occurred…
… As with insider dealing, the arguments in favour of short selling are impeccably logical. Economic theory suggests that short selling contributes to accurate share valuation since it enables share value to reflect the negative perception of company performance that market participants have formed. In this way short selling promotes an orderly adjustment of the stock price.
The topic revolves around information, and the communication thereof. Insider traders enjoy privileged information, which is bound to come from intimate knowledge of management personnel, strategy, operations and risk positioning.
In that case, sell-side research, already hamstrung, is not going to be worth a tranche.