First, you should have included the essay prompt in your post. Then we know exactly what it expects from you. Also I understand you are preparing for TOEFL (you have mentioned that in one of your other essays). Do mention this purpose in every title because that helps you draw others' attention. :)
People nowadays are concerned more about the clothes they wear.
...Need a little re-arrangement of the words;
Nowadays, people are more concerned about what they wear.Some people enjoy wearing formally, while others like to wearthe casual clothes.
Personally, I think that wearing politelycasually is still critical in our recent society because wearing formally can create a good image of you in front of other people and wearing politelycasually is a way to show the respect to the opposite people.
... "wearing casually" makes sense, but not "politely". Also, this sentence is a bit confusing, especially the latter part of it. Write a simple sentence that expresses your opinion;
Personally, I think it is important that people wear formal dresses.