You don't have a choice as to whether you have a profile or not, so it's a moot question. Everyone gets one. Some people don't want strangers digging through their stuff. Makes sense enough to me.
Not hacked. Some people just don't want others to have the ability to go through all their questions and answers. They prefer some privacy or don't want to be an open book. A lot of people give very personal answers to things or are very sensitive. It makes sense that, if they use the site to relate to specific individuals on a very personal level, they wouldn't want to air it out to everyone.
I find that the more personal someone's answers are, the more likely they are to hide their profile. It's just an extra layer of anonymity.
I'll tell you I have never been able to this day, to get into my old questions. No matter how hard I try. It's a glitch between my computer and this site. It would be fun to get in there.
Just Asking 