The project was originally called clawdbot as it was based on Claude. Pressure from Anthropic made Peter change the name to Moltbot, which everyone thought sounded gross, so he changed it again to openclaw, with a lobster mascot.
Because it's a buzzword. It causes buzz. Putting it together with "world" makes it buzz even more because people want to talk about world models all the time (it doesn't matter what the actual input and output is, just that it's a world model, not some meagerly language model, it models all the world, much better than modeling just boring old language), as well as about claws. So that's why.