Usually because people didn't get the username they wanted in time and are too lazy to think up a new one X)

Because of the reasons above, and also because some 8 year olds want to look cool.
Example:
XxXxePicsNiPaRlEGioNlEgeNdDZoFwArn0sC0pEn00Bz#y0L0swAg#2d0pE2c0PeXxXx

ME1312I just wanted to know why people like names like "XxXwhateverXxX"

Honestly it's better than seeing a username like banana123.

My PMC name was my old mc name (account gone now) and I hated it. CraftAeternalis is my current one.

I just don't want to bother with getting a name change on pmc.

[deleted]

Err, how about me though? Oftentimes "Snowyfox" is taken, so I just append '16' to the end. These days, I bypass that entirely and just use "SusuKacangSoya" instead. Alternative names are better; xX may be nice but makes you look quite young (it's good of a username for a young teen but a 20 year old probably shouldn't be using xXXx).

WHAT ABOUT ME HUNMMHMHMHMH >:_)

We'll TheArcher was already taken. So....

Mine was-- and still is-- that way for a long time on pretty much every service I used just because "Azie" is always taken. I just needed some extra characters that didn't look weird.

Because it sounds original probably

They probably think it looks cool, and typically the name they want is already taken so they put Xx, etc. on the outside to make it look better, instead of numbers.

Just my theory.