I think you have to look at the time frame and history of when AutoIt and then AutoHotkey came out. What they were doing on the Windows OS was not so feasible with JavaScript. But AutoHotkey, and AutoIt to a lesser extent, have always used JavaScript in a supplemental way when possible.
As for Python (on the Windows OS) it doesn't come preinstalled, is far larger, less specific to automation, more confusing, and less convenient. There has been numerous Python attempts and projects to copy or make something similar to AutoHotkey and AutoIt, but they never caught on as much. AutoHotkey and AutoIt had already gained a reputation and became more firmly entrenched as the tools to use for automation tasks on Windows.
AutoHotkey has a huge support forum history in addition to great documentation. The language it uses seems terrible and confusing, almost as bad as bash! But if you want to do something chances are it has been done and there is example code already there to get your started, a lot like bash. That is worth a lot more than it having a better language at the end of the day.
JavaScript. To script Windows. Whoa.
AHK is directly calling Windows' DLLs. We don't need another translation layer, and Python already has some libraries to accomplish similar tasks.
As for Python (on the Windows OS) it doesn't come preinstalled, is far larger, less specific to automation, more confusing, and less convenient. There has been numerous Python attempts and projects to copy or make something similar to AutoHotkey and AutoIt, but they never caught on as much. AutoHotkey and AutoIt had already gained a reputation and became more firmly entrenched as the tools to use for automation tasks on Windows.