Turner was somewhat popular here. I find it tough to argue with this move, though. Yes, Turner is big. That does not mean anything if you do not know how to use that size, though. If big was everything, the Jets could sign Amare Stoudemire to play wide receiver.
I think it comes down to the following things. A guy at the back of the depth chart's value comes primarily from special teams. That is the only time he will see the field. With four receivers in front of him on the depth chart and Dustin Keller (as well as Joe McKnight and Jeff Cumberland) capable of splitting wide, Turner would not have even seen time in five receiver sets. Since he is not a special teams guy, his value to the team would have been zero. On top of this, as much as people talk about Turner as a developmental guy, he is in his third year. If he is not ready to make at least some contribution now, when will he be?