Not sure about other getters but GetChildren and GetDescendants at the very least I would love to have predicate support for. I often find myself writing my own especially since I am an avid subscriber to single-script architecture and have converted every project I have signed onto into that paradigm.
It is very common for codebases following single-entry-point logic to need to query only ModuleScripts for example and I find myself writing tons of pointless boilerplate for the same thing every time (specifically: I use a package that handles traversal and requires for me wherever I can).
There are other APIs in the engine that allow predicates during traversal such as PreloadAsync (though this is only a rare example? and the callback is ran after the fetch, not before).