I have no complaints with these languages. I have only seen them used to program PLCs to control machines and processes, and the simplicity of the languages keeps programs simple and straightforward too.

What features are missing that you think belong in process control?

The languages aren't so bad, but the ecosystem is rough. On the PLC vendor side, implementations vary widely and they're all proprietary, so for a given controller... what they give you is all you get. On the programmer side, skills vary widely and ladder logic is the common denominator, so a lot more is written in ladder logic than is appropriate. For instance... Complex sequential logic (like a machine with many adjustable operations, all controlled by an HMI) is difficult to convey clearly in a ladder logic program. It can be done... but all I have ever encountered is lots and lots of spaghetti logic.

I wish I could use sequential function charts to handle some of the complexity in the machines I work on, but the PLC models we use don't even support them. Argh.