You are just not used to it.

> the way the command line works: no feature to repeat previous comnand with up arrow, have to edit previous existing one, requiring more mouse usage, weird forms of cursor placement, weird default enter key behavior.

It's not a command line. It's an interactive notebook. It's an entirely different experience. Repeating and modifying last commands can still be done with arrow keys, then Shift-Enter. Also, when you are doing math, you spend way more time thinking than typing and manipulating; the time needed to move your hands to the mouse is minuscule by comparison.

What command line are you talking about? If you want a command-line IPython-style REPL, enter MathKernel, which absolutely does support arrow keys to go backward and forward in history (and works over SSH without X). If you want a IPython (later Jupyter) notebook-style interface, enter Mathematica/Wolfram notebooks (guess where IPython notebook got its idea from). Sounds like you just didn’t bother to learn a bit about it before making up your mind.

You're missing cmd+L (copy last command to cursor) and cmd+shift+L (last result).

Although, as others have said, many prefer the style of editing and re-running, rather than leaving the history above.

Mathematica Notebooks have some REPL-like aspects, but they really should be uses like a script editor that shows the script output inline. You can jump between script segments and execute them out of order, which is useful in some cases. But notebooks are at their best when you have some discipline when editing, so that they stay in a state where you can open them, select execute notebook from the menu and everything works on the first try.