I have another view of why so little ID is being incorporated into TBT that relates to the fact ID is taught as a very dry and linear process with little emphasis on creativity. In the interest of making it appear "scientific" we often take out the role of creativity and imagination in designing the instruction.
Thus for example Gagne's nine events are presented as a lock-step structure (in a manner that he never intended, by the way) in which one follows closely a script that goes something like this: "Make sure they are awake and then tell the students (probably in very stylized form) what the objectives are, after which you tell them a bunch of information and ask them to recall it, and don't forget the drill and practice session and be sure to tell them they are right or wrong."
It reminds me of the old Skinner programmed instruction formula for design. The result is instruction that may work (if carefully tested and revised), but is boring as hell! And of course, higher level outcomes are conveniently ignored.
Is it any wonder people reject this kind of ID?
Make no mistake, I firmly believe ID can (and sometimes even does) produce effective, interesting, and challenging instruction, but not when design becomes a follow-the-dots-process.
If we want to know one (and only one of several) of the reasons for the lack of acceptance of ID it is the way it is taught with all the creative juices squeezed out.