I'm still waiting...
I know there's a lot of rose tint involved, but things like ARexx, datatypes, screens, and assigns still feel hopelessly missing.
Every time I get a file open dialog without a list of assigns I can also use in the shell, for example? What is that bullshit.
I've started building small things to paper over the worst of it for my own use, but it also makes me wonder how many other great innovations I'm unaware of that we've largely forgotten about.
Being able to simply write to the SPEAK: device was nice