To start with, evidence from social psychology indicates that humans possess a bias toward detecting and avoiding danger. Social psychological research shows that “losses loom larger than gains” (Kahneman & Tversky, 1979, p. 279). The psychologist Csikszentmihaly found that negative thoughts were 'stickier' than neutral ones, particularly those emphasizing danger. So evaluation is a core process of survival - very useful.
However, as Hayes, Gifford, & Wilson explain (1996), language extends the impact of the evaluative process beyond the immediate situation: "Human [language] means that people respond to a situation in terms of how they relate it to previous experiences and to future events. Given the tendency to emphasize losses, they may harbor a bias toward seeing the situation as threatening".
Evaluation is rarely, if ever, objective and has a tendency to reinforce existing stereotypes and self concepts, many of which may have caused the problem in the first place. This is something I have referred to in the past as functional fixedness. The trouble is, our minds (bless them) often do not detect this bias.
The dangers of evaluation show up in many other ways. For example, if someone has had an ambiguous encounter with a coworker may then they may interpret this negatively and act in more guarded ways in future, making further negative interactions more likely. A study by Biglan (2009) showed how 360 degree feedback in a school backfired and resulted in hurt feelings, resentment, and resistance, even when that feedback was largely positive. Supervisors, who themselves felt punished by these negative reactions, tended to avoid giving feedback.
Evaluation is useful in a career change but it is only one tool. It should be used with care. Rules and evaluations and judgments can help us, but they also have the ability to trap us. Words, ideas, concepts, identity - all are useful to help us describe reality.
But they should be held lightly. They are not reality.