Bitachon is knowing that there are problems and trusting G-d to work them out. There are things to be critical of. That s the power behind a successful effort to cope with problems. With that wisdom, criticism is the first step to a positive effort to deal with the problems. The critical and the positive eye work together to take matters in hand and make them better.
Children build up by knocking things down.
They re just critical. They respond to problems by being negative and destructive. That s immature. Mature people deal with problems in just the opposite way. When they want to knock something down, when there s a problem that they want to overcome, they build things up.