Poison Pills: Who is Right?

Shareholder activists are continuing to attack poison pill plans as shareholder unfriendly (20 percent of the Fortune 500 companies still have them in place).  We are told by academics, however, that it should not matter.  All companies can put them in on a moments notice so all companies have "shadow pills."  Are management and shareholder activists wasting their time battling over actual pills or are the academics right?  I vote with those in the trenches; actual pills do matter.  They signal management intentions and it is easier for the board to refuse to waive a pill than put one in when the board is under threat.