Because it's an absolutely massive code base that requires access to some serious HPC resources, which basically makes it difficult if not impossible to reproduce for most people. Putting something out there like that also implies something of an obligation to maintain and support it, which isn't what we do.

There's also a weird data rabbit hole. Is the code that generates the simulation data enough, without the underlying data that code uses? Some of that is either protected or proprietary, so even with the code, it's utterly useless.

Simulations may run for weeks or months on large computing clusters. People wanting the resulting data may not have suitable access and/or resource allocations to repeat the runs.