I agree, also believe that names must be public. Too much corporate, PAC, 'SuperPAC', big 'organization', and foreign dollars in US campaigns. At least voters will know the the money behind the candidates.
About that transparency issue in political advertising; there are people and businesses that have been targeted by opposition groups for supporting a candidate or party, to the point where they withdrew their support. Why should a business or person not have the right to free speech with privacy, same as your right to vote in private?
Our problems with governance and campaign financing are not going to be solved by limiting free speech or by outing who supports who, either individuals or companies. We need a better informed and more involved public, that is the real answer.