I know it was mentioned earlier but I think it´s worth to raise this debate again.
I heavilly use history in Rhino 5 and I suggest it to all people when teaching Rhino. It´s really great tool for conceptual design, of course you must be aware of it´s limitations. I especially enjoy chaining more history enabled commands together, which results in very intelligent and almost parametric objects.
But I really miss one thing - being able to change command parameters, not only input geometry. When I show people array commands with history, I am usually changing input objects (rebuilding them, deforming using CV´s etc) and all array instances change accordingly. Everybody say: “Hmm, this is nice, and now change the number of objects”. They can´t believe this is not possible.
I don´t ask for parametrical tree like in CAD programs. What i am asking is some more robust history. When I click to some object with history, I should see all commands that were used to build it and I want to be able to change it´s parameters. In my wildest dreams I can even imagine that this would be accomplished by some extra-light version of Grasshopper. Clicking on some object would rise some Grasshopper-like object/command tree, something like on this image (simple loft with 3 curves):
And of course more history aware commands would be great - trimming, booleans…
What do you think?