1. Earnings of 501(c) organizations can't inure to the benefit of individual shareholders.
2. 501(c) organizations can't actively engage in politics and influencing legislation.
3. Public disclosure requirements and accountability.
Just to name a few of the more obvious problems. Of course, some of these problems might exist as a matter of law, regardless of 501(c) status, by accepting donations and holding one's self out as a non-profit or charity.
#1 and #3 look simple to solve. Regarding #2, the following is from the regs from what Liberal Classic posted in #1497:
(c) (3) (h)), and which does not participate in, or intervene in (including the publishing or distributing of statements), any political campaign on behalf of (or in opposition to) any candidate for public office.Did FR formally endorse a presidential candidate? If so, I don't see any great loss from refraining from doing so in the future. I think FR's mission statement mentions "conservative" but not Republican. Aren't similarly biased (or oppositely biased) organizations structured as non-profits?