The exact language in the Constitution on what justifies impeachment is, "treason, bribery, and other High crimes and misdemeanors."
That's vague, and the Founders intended it to be.
Impeachment is a political process. You'll often hear people answer the question "What is impeachable offense?" with "Whatever a majority of the House says it is."
I embrace censure because it draws a line in the sand, a motivator for better behavior, and as a form of mild punishment.