Blockland 0002 was the first thing I had to make up an online name for, but, stupid as I was, couldn't figure out how to change my name, so I stuck with the default name, Block dude, which I also joined to forums with, even though I knew how to choose my own name. When retail came out, I found that the default name had changed to Blockhead(Insert number after ID here) Which simply made me feel like I was being labeled. When I figured out how to change my name in retail, I was still rather attached to any name with 'block' in it, and the only reason I stuck with block dude in 0002 was to show I didn't care that my name was the default name. (brought on by frustration, I was rather young at the time...) So I slapped the name Mr.Block in the player name bar, then after something happened on Jookia's server (something about mutants with green skin and an under staffed island hospital) I changed my name to Dr.Block, which I, for some reason, thought more fitting. So I stuck with it.
tl;dr: I got lazy and stupid.