Why do people use custom huds? What other customizations do you recommend?

I've been playing for almost 1000 hours, and I've looked into custom huds, but i don't see the appeal in them. I essentially have tf2 the way it came out of the box (yes, the box). I used a custom crosshair for a while, but I've switched back to the stock ones since then because I like how they change depending on what weapon you're using. The only customization that I've done (if you can even call it that) is installing Chris' config, a mario coin noise dingaling, and setting some custom launch options (little things like no mouse acceleration, windowed, novid, high priority, and set tf2 to use a certain amount of RAM).

So my question for the community is why do people use custom huds? Also what are some other customizations that you have personally made to tf2 or that you recommend?

My apologies to people that have seen this question hundreds of times.