It's about numbers of votes and how to get them.

[merrily]

7. Hstory shows that attempts to court big donations have taken the country in the direction

big donors desire.

You cite one example from state government in the Sixties. That doesn't exactly make the case.

How about something more recent, like the effect of the health insurance lobby on the ACA? Or the effect of Debbie Wasserman Shultz's donors on her initial position on payday loans? She's changed it and my guess she did changed her position only because of a strong challenge from her left. Perhaps the most dramatic example of this to Democrats is the NRA influence on sensible gun control legislation. I could go on and on.

Conversely, what potential evil do you see as a result of limiting ALL donations to $2700 from individuals? Isn't a level playing field the point?

Which reminds me: "Corporate" is something of a misnomer. It's any huge donor who wants something, but it an individual, like Koch or Adelman or an association, like the NRA, or a limited partnership or a trust, etc. "Corporate" is just a catch all.