You’re describing a command-line interface and I’m describing a GUI. My point is that you can keep your command-line conventions where they belong, without requiring them in the GUI.
But actually, the commas indicate that another number is coming. The spaces are clearly required between Line and 0, and between 0 and 10,10,10, but that doesn’t mean they need to be forbidden between the 10s.The commas tell Rhino that another number is coming. The command-line language doesn’t need to be as rigid as it’s defined.
But that’s beside the point. In a GUI, the spaces don’t even cause the problem you’re describing. If you imagine three separate fields to enter the three coordinates, then I should be able to paste in 10,11,12 (without spaces) or 10, 11, 12 (with spaces) into the first field and rhino would have enough information to distribute the three numbers through the three entry fields. This way, the spaces are actually helpful rather than harmful. Command-line conventions aren’t needed in a sensible GUI.
Did you try entering the values in through the GUI like I described?