The Supreme Court in a 5-4 vote ruled that corporations and labor unions may now spend freely in federal elections.
This question comes down to whether one believes in absolute natural rights interpretations of how our legal system should be run, or whether we think the law should be used to support some ideal of the greater good.
Natural rights law believes that liberty is important. Infringing upon that liberty is a larger problem than whatever might result from it. Legal posivitism states that the law ought to shape a better society and liberty is less important than that goal. Certainly those that voted to retain the prohibitions fear the results on the election process. Those who opposed the laws use free speech arguments in their favor.
The fact is that these prohibitions do not keep this money away from elections. All they do is to force the money to run an obstacle course to get to its final destination. Without a lot of investigation, it is hard to figure out where the money came from. In any event we spend more on elections now than ever. Where would the national economy be without them? Without prohibitions, we are more likely to see the real origin of the money spent on elections. That is a transparency that the process has lacked for some time.