Hah!
There's definitely the kernel of an idea there, an "expression library" or something. There's nothing, technically, preventing us from doing it, but I'm still not totally sure it passes the -100 points rule.
I can immediately think of at least four more-and-less significant drawbacks:
- added complexity for less advanced users
- "competition" with
runScript - possible confusion of maintainers having to distinguish system expression functions, module expression functions, and user provided expression functions
- interaction with (far) future plans for expression/scripting interpreting in Ignition
Are those worth the added maintenance benefits to large scale systems trying to DRY things out? I'm not convinced yet, and the default position is "don't".