The translation that you picked is wrong. The more accurate translation is by shakir
And say to the believing women that they cast down their looks
and guard their private parts and do not display their ornaments
except what appears thereof, and let them wear their head-coverings
over their bosoms, and not display their ornaments except to their
husbands or their fathers, or the fathers of their husbands, or their
sons, or the sons of their husbands, or their brothers, or their
brothers' sons, or their sisters' sons, or their women, or those whom
their right hands possess, or the male servants not having need (of
women), or the children who have not attained knowledge of what is
hidden of women; and let them not strike their feet so that what they
hide of their ornaments may be known; and turn to Allah all of you, O
believers! so that you may be successful.- Shakir (Quran 24:31)
- A woman should guard her private parts. This most likely meant bosom, but applies equally other private parts well.
- A woman should not display her ornament (bangles, necklaces, anklet) to men other than what is mentioned in the verse above, that is husband, father-in-law, sons, sons of her husband (of another wife), her brothers, brothers sons,sisters sons, other women like her, slaves, and servants who do not have desire for women or children who are not familiar with a woman beauty (that is they are not attracted to women).
- The should not strike their feet, walk the way to draw attention to her ornaments.
So I think the term beautify is being misquoted here. It is verse related to all women, not just beautiful women. As far as I know, there is not such term as beautiful women or men in Islam.
As far as your question, A muslim women must wear hijab regardless of weather she is beautiful or not (unless someone can correct me). Note that I have answer it in general way. They may be specific cases that I have not addressed.
If you need more explanation, please comment, so I can explain better.