The reason we have safeguards against things like illegal search and seizure is because government is the greater threat against our freedoms, not individual criminals. By making such tactics in pursuing even legitimate convictions fruitless, in other words by throwing out cases where such tactics are used, government is less likely to use them for illegitimate purposes. Thus, we are safer from government intrusion.
That's why this kind of thing gets such scrutiny. I don't find it inappropriate, necessarily, but I do see how it stretches the bounds of acceptability.