This detail came up on Quora some years ago. It says a lot. I will use pictures (colorized) already found in answers here as they illustrate this important point.

Nimitz and MacArthur didn’t miss any details….below we see

Formal dress. Cavalry boots with spurs, gold braid, white gloves and tuxedos of a sort. Meanwhile allied officers were given specific orders…

“All personnel, Khakis only…dress for work.”

The only guys in their dress whites in the photos?

On the left of the photo, enlisted hanging from whatever they could grab onto to witness one of the most extraordinary events in the history of the world. Straight ahead in the center of the photo you see a group of “sideboys” and the boatswain’s mate(s) in their dress whites who took position and “manned the side” for the arrival of countless allied officers, but also the Japanese delegation…..everyone else?…khakis.

Finally, our two “hosts”…

Couldn’t even throw on a necktie.

General Jodl signs the surrender for Germany? Room full of guys.

Japanese sign the surrender? They brought the whole fucking fleet!

It was all about symbolism. The US wanted Japan to realize, without a shadow of a doubt, that they were a defeated nation.

Parking a US Navy battleship in the harbor of their capital city… surrounded by a large flotilla of other US Naval vessels…… and forcing them to come aboard for a surrender ceremony did just that.

Japanese Surrender Delegation to the USS Missouri

Japanese Surrender Delegation Aboard USS Missouri, Wider View

When the Japanese delegation came aboard, they saw Commodore Matthew Perry’s flag on display (upper-left corner):

Allied Delegation Aboard USS Missouri with Commodore Matthew Perry’s Flag

This is the same flag flown by Perry in 1853–1854 when he traveled to Japan to force them to open up trade with the United States.

Additionally, the USS Missouri was parked in the exact spot as Perry’s flagship had been anchored almost a century before.

Japan’s Foreign Minister Mamoru Shigemitsu Signs the Official Surrender Documents

Immediately after the surrender ceremony ended, hundreds of US fighter aircraft did a flyover as a demonstration of power, just in case the Japanese had second thoughts about their surrender:

US Fighter Aircraft Perform a Display of Power Over Tokyo Bay for the Japanese Delegation

There was no formal reception afterwards. The Japanese delegation was promptly escorted back to their boat for the mainland.

Not to mention the fact that the USS Missouri was named for US President Harry Truman’s home State.

Japan is a proud country. All this was particularly humiliating for them, which it was intended to be.

After WWII, the United States didn’t want to repeat the mistakes that the Allies made with Germany after WWI. With that in mind, the US instituted various plans to rebuild Europe and Japan, instead of just leaving them in ruins and starvation to fend for themselves.