Gender
Gender, with all the baggage it brings, is impractical. Most people are more similar to each other than they like to feel, so they impose all these weird constraints on their lives (and others' lives, too!) to maintain a gross and impossible aesthetic.

The “Mar-a-Lago Face” is an infamous recent example of this problem. Women of certain political conventions mutilate and degrade themselves for men who are equally malformed and live in equally gaudy houses.
Conversely, one’s gender (or the lack of it) can be a canvas for beautiful self-expression.

Most people agree that censoring art is harmful, yet many of the same people support politicians who push for laws against unusual gender expression. It’s ridiculous and contradictory, no such draconian laws should exist.