Nonsense. From wiki: "The term "money laundering" is said to have originated with the Italian mafia and such criminals as Al Capone who allegedly purchased 'Laundromats' to commingle (or mix) their illegal profits from prostitution and bootlegged liquor sales with legitimate business sales"
But furthermore I don't think it needs to be argued that people have been hiding money from governments since there has been money and governments. It will always be an implicitly illegal act regardless of the existence of specific statute because you are in the end avoiding taxation.
It's usually highly illegal because it involves falsifying records, including those filed with tax authorities (and because the purpose of that falsification is to conceal another crime.)
EDIT: My point (to the downvoters) is that not all "illegal" activities are immoral, and that reasoned people could legitimately consider willfully defying & hiding their defiance as an act of freedom. Case in point: Tea in 1773.
Neither of these claims are true.
"Money laundering" as it is understood today only emerged in the 1980s during the war on drugs.
It's a crime because it's easier to prove and prosecute than any actual crime that might be facilitated by anonymizing money, like tax evasion. I'm not sure if that's a good reason, although it is a practical one. It's kind of like making encryption illegal because people might use it to break copyright law. The use of encryption isn't the actual crime, but it's easier to prosecute.