Being able to critique things is really important. It's essential for identifying problems, developing good ideas, and improving systems and products and well as people's personal development.

You say to explain how things could be improved rather than talk about the problems with them. The problem with that approach is it's usually important to first identify exactly what the problem is, before coming up with ideas for how to fix it. Sometimes it's not obvious how to improve things. It may take days or weeks to get to that point.