Is wearing a shirt over trousers when entering the mosque for prayer considered an act of wisdom, or of extremism and incitement to discord?

Prayer in pants is valid, but it is better to wear a long shirt over them, because it provides more coverage, especially if the pants are tight and define the 'awrah (private parts) or if there is a fear that something might become uncovered during prostration. The long shirt covers the 'awrah and completes the adornment.