Building a mosque on or near Ground Zero was a recognized right by virtually everyone. The issue was one of appropriateness, not rights.
Yes, you are right that WWII was the last declared war and your point is.....? Before that scumbag socialist, FDR, and his third term, our forebearers thought this was so important that ery war of any substantial length or destructiveness was declared before that. It was iron-clad precedent from the first major war after the Constititution, the War of 1812, until WWII. It was recognized a valuable restraint on executive power. A simple "approval" does not fit the Constitutional requirement.