Worker rush: Why do people do it?

Why do people worker rush (right when a match starts, you send all your SCVs/probes/drones to the opponent's base to attack their workers)? I have had this happen a couple times in 2v2 matches, and it just ended in messy games where they either lost immediately or lost eventually. I would never consider doing this in my own games, and I always wondered what the compelling reason would be.

Since there is almost no decision making at this early stage of the game, there is no advantage to play from really. So, what could the rationale possibly be? Here are my theories:

• In low levels of play you could hope that your opponent doesn't know how to attack with workers, so your own workers attack with no repercussion.
• If you expect a 6-pool, maybe you can have an advantage in worker numbers because they cut all drone production?
• Maybe you are just messing around doing something senselessly
• Maybe you have to go soon, so this is at least SOME action instead of a cold surrender.

As for defending a worker rush, see these other questions:

Best strategy against Worker Rush cheese in 2v2 and other matchups

Drone Rushes: Counter for each race

Solution 1:

I'm going to tell you a story, and I hope it illustrates why people worker rush.

Back in 2003 MBC did a champions play off, and in the finals SlayerS_Boxer faced off against [NC]Yellow (probably the best player to never win an MSL). Boxer spawned in the 11 o'clock position and Yellow in the 7 o'clock position. Boxer scouts south and Yellow scouts east (missing the scouting SCV). Boxer goes for a 2 Rax opening and Yellow a FE... except Boxer scouts the Hatchery as it goes down and, in what would be one of the most memorable moments of pro Starcraft, he pulls his SCVs to back his only two marines... and RUSHES!

Even in retrospect it is an amazing game to watch (even more amazing than FruitDealer's 6 pool in the finals of GSL1 2010), but it illustrates the power of the move; Worker rushes (and all other early rushes) are designed to punish your opponent for over extending himself to try and gain a lead. Many players (even pro players) will cut corners in their builds to gain a Macro advantage (TLAF'Ret is a huge fan of this). In these cases the early rush serves to keep these players honest.

This same concept extends to 2v2 matches, except instead of a Macro advantage being conveyed by Fast Expansions, its conveyed by not joining armies. If you can stop your opponents from joining their armies together you have the advantage of fighting two 2v1s (which is easier than one 2v2). A very early double worker rush provides for the ability to do this as many 2v2 teams do not help eachother out in this situation.

Solution 2:

They are doing it because they are achievment scumming.

Say you need to get 50 wins for some portrait or another. Which is easier, going through roughly 100 legitimate playthroughs that take an average of 15 minutes, or doing 400 playthroughs at 90 seconds a piece where you have maybe a 25% chance of winning?