Its simplicity is an important part of the offering. Bash is perfect when you need predictable executions.

When you use Bash, you benefit from an entire ecosystem that also uses it. That same ecosystem is not motivated to drastically change the shell, and therefore it remains stable and predictable.

Bash typically isn't like Python or JavaScript, where certain features are introduced at a particular version and you have to constantly check for them, or not use them outright, or maintain which binary you have installed at all times. One Bash binary typically contains the same feature set as another binary.

Bash isn't the friendliest thing to work with syntactically, but it's friendlier than the alternatives in maintability and reliability.

Despite all this, on the flip side, there still are a lot of people invested in alternatives, and some have gained plenty of traction. zsh is a great example.