I do completely agree with you that we ought to transition toward structural code editors (and therefore, I suppose, structural terminals), but as you say, that's a very hard problem -- I have yet to see one which isn't terribly clumsy to use.
VOPs in SideFX:Houdini are the best use of code-with-nodes I've ever used.
You 'write' your code as a network of nodes, then on the fly it is converted to vex (a houdini internal scripting language) and compiled, the result runs very quickly.
If you would like to check it out, get Houdini Apprentice and have a play with the 'VOPsop".
