1) I think the Supreme Court decided correctly that if the Constitution gives individuals a right to freedom of speech, the right doesn't go away if they use a corporation to exercise it. The New York Times is published by a corporation, after all. Do we really want to say freedom of speech only applies if a sole proprietor is speaking? I don't think so.
2) This isn't the end of the world.Once upon a time corporations could spend freely to influence elections. Then laws were written to limit this. How much did the political landscape change afterward?
If you can identify a new law that limited corporate influence on the political process that actually changed outcomes in a measurable way, please post it here