Touch screens are interesting because they build on the sorts of visual skills that we use in daily life. The command line is interesting because it nurtures skills you can't get from wandering around a garden. If I want a child to build their visual skills, I want to get them out in nature, or playing with physical toys, not a touch screen.
A CLI on the other hand is a very good abstract reasoning thing - it's on the same level as teaching a kid to read, or counting. And like reading I think it's a very valuable exercise whether the kid "gets" it or not.
It's only good for abstract reasoning if you can manipulate it and understand what you are doing. Kids at that age can't manipulate it the way you seem to suggest. They can "only" (if I do X, Y happens). It takes pretty intelligent kids to be able to be creative about that at such a young age.
The iPad on the other hand allows for emulating the reality the kids know and thus allow them to play around and learn abstraction based on where they are mentally.
A CLI on the other hand is a very good abstract reasoning thing - it's on the same level as teaching a kid to read, or counting. And like reading I think it's a very valuable exercise whether the kid "gets" it or not.