1. Any question that starts with "why" is calling for a defensive response. You might as well say, "Defend yourself on this point!"
2. The question comes from a point of view that "__fill in the blank____
3. The question calls power into the relationship. It says, "You have the power to make me respond to whatever idea you have, regardless of how ill-advised your idea is."
4. The question assumes that I do not have the ability to develop my own solution from the options that I consider. It says you do not trust me nor do you value my competence.
5. The question keeps me distracted from doing my own work and instead focuses me on trying to make you happy by my response.
So, what you think might be a helpful piece of advice is quite often a shaming, de-valuing, dis-empowering, low trust, defensive move. Yikes!
When I feel compelled to ask someone "why don't you just...?" I can stop, take a breath, let go of my need to be right, and then ask a really good question. And if I've exhausted all the good questions and still feel compelled to give my solution at least I can ask, "Are you open to hearing the solution I've crafted for your life?"