In the beginning, there were the rules, handed down from the proverbial mount. Thy suit shall be thy prison, in sturdy black, navy blue or gray. Thy feet must ache in polished brogues. Thy weekend wardrobe alone should be a comfort.

But in the midst of a veritable boom in men’s wear, a funny thing is happening: The rules (even the suits) are loosening up.

“The men’s wardrobe has evolved immensely,” said Tomas Maier, the German-born designer of Bottega Veneta, the Milan-based luxury label, and of his own more-casual namesake line. “There’s a lot of men out there who do not need those sartorial codes. They’re not lawyers, they’re not working on Wall Street. Including myself.”

In recent decades, following the avant-garde Armani billow of the 1980s, suits had mostly settled into a comfortable rut: stiff, dark, breaking just so over the loafers, so uniform as to be barely noticeable.