Project managers often resist process change because any innovation has unknown risks associated with it.//////////
Project managers are judged according to whether or not their project produces software on time and to budget. They may prefer an inefficient but predictable process to an improved process that has organizational benefits, but which has short-term risks associated with it.
Engineers may resist the introduction of new processes for similar reasons, or because they see these processes as threatening their professionalism. ////
That is, they may feel that the new pre-defined process gives them less discretion and does not recognize the value of their skills and experience.