Modest and appropriate attire is an integral part of devotion to Salah. Attire demonstrates a person's mindset and attitude. This verse emphasises the importance of modest attire in Salah. We can appreciate the choice of words used in this command, that not only is covering one's body implied, but implicit reference is made towards a distinctive type of attire. The word “Zeenat” (i.e. dignified or appropriate attire) in the verse implies cleanliness, beauty and dignity.
During Salah, merely covering one's 'Awrah' (the area that is compulsory to conceal) is not sufficient, but clothes that are befitting of the sanctity of Salah must be adopted. (Ma'ariful Qur'an)
It will be inappropriate (disliked) to perform Salah with attire that is deemed immodest or disliked, or generally attire that a person will consider improper to wear in public.
Performing Salah with tight fitted clothing, bright colours, or clothing that exposes areas of the body is contrary to the spirit of devotion in Salah. Consider who one is praying to and dress in a manner that brings devotion and humility to one's Salah.
A person who has to meet with a dignitary, or a person of worldly importance, will ensure that he dresses appropriately for the occasion. Salah is to meet with the King of the Universe. The dress code should be most sublime and dignified.