Yes, it is convenient to live near where you work, especially in big cities where the traffic is terrible.
But, if most of your colleagues live in the same neighborhoods as you do, it is just weird. I am two different person when I am off work. I may walk randomly around in my comfortable clothes, argue with my child or my family on the street or take a musical lesson in some training center. I don't want to run into any of my colleagues . I want to have a free life that my colleagues may never understand. Plus, living too near the company feel like you have never off your work. So, that's why.
There are people who don't mind to show who they are. Some of my colleagues wear really tight exercising leggings to work, obviously they are going to do some exercise after work. This is great. Do what you want and avoid what you don't want, as long as you are happy and healthy.