What you're suggesting would mean we can practically forget about warrants, especially in big cases. The prosecutor just needs to find an officer ready to take a punishment and he can get his evidence in any way he can.

And what about civil cases? I'm pretty sure there would be much more illegal surveillance if the gathered data could be useful in courts.

You're questioning some basic principles of our legal systems that are here to protect us. I agree that it's sad to see how far corruption can go and it's also discouraging to see criminals walk on technicalities, but those issues should be solved differently, not by reducing the scrutiny on obtaining evidence.

See [Blackstone's formulation](https://en.wikipedia.org/wiki/Blackstone%27s_formulation) and [Exclusionary rule](https://en.wikipedia.org/wiki/Exclusionary_rule) for a more detailed explanation.