I don't agree. If referred to the third umpire, the benefit of the doubt goes to the batsman. Hence, if it is too close to call, then the batsman should be not out. Which is why the umpire doesn't really do a mental coin toss. If the batsman is shown to be caught out clean--he's gone.
I agree that the batsman should get the benefit of doubt (the debate is on the extent of doubt given the fielder's word), but good decision-making is also about narrowing the extent of the grey area. I still think the mental toss happens often enough, even if it does not involve a fair coin and 50-50 odds. In my opinion, this is really a question about our own perception of the integrity of the current crop of players and how to deal with it best. One could get all misty about the good old days and take the high ground about the cricket we used to know and love, but the ground realities (weak pun intended) seem to suggest that one should not put more trust than what the players have earned.
But any evidence that will later show that a decision was wrong can, in principle, be applied before the decision is taken (for example, by the third umpire). What remains is the small bunch of instances where only the fielder knows what happened, and it is not clear to me that a glum view of human nature is our best guide in the matter.