I guess it is a part of a vicious cycle. And this does not mean I favor some/rare insider trading. It must not happen at all to preserve the integrity of financial markets which drive the globe in all ways.

When economy is booming, everyone tries make more money to save their jobs and their company position. No one bothers to investigate why he or she or they are making insane amount of money. But when everything cools down and if that cooling down turns in to a recession or freezing of liquidity, authorities wonder why these have happened. And they start investigation, they find culprits. All get warned. Temporary freeze in insider trading. And again, when economy picks up, competition to make money and to chase big traders/ banks begins.