A couple of points on this one.
1) Perhaps back in the day people were more gullable and or the tricks were more believable.
2) Don't forget that if you go back far enough people actually believed in sea monsters, dragons, and that Paul Daniels was good entertainment. The constant drive of (most) of the Human Race up through the IQ scale is making it more and more difficult for people to suspend disbelief.
3) I think the backlash on here is more to do with rational people reacting to those who did not see it as a trick, but as a real thing, that Derren Brown really has some sort of magical powers,..rather than ridiculing the spectacle itself or Derren's delivery of it.