Great points! I just tried out it in windows explorer just to check. It is similar, but at the same time very different. It is true that selecting multiple images and hitting enter will open for me multiple instances of my image viewer, but, there's a crucial difference. Windows explorer is built and optimized for (to me slow moving/not so efficient) clicking people. Due to this clicking interface yes, you can select mutliples files, but only by holding ctrl & then clicking at different positions in the 2d plane. That makes it less of a problem, and to make it a complete non-problem whenever you manually move focus of a file with arrow keys the selection resets (often resets would also get rid of the problem in MC). In explorer there is no way to select a file and then use the arrow keys to move past a couple and then select another one.
Howeeever, MC is by design a tool oriented for more keyboard and shortcut use. I never use the mouse to jump around files in MC, always the keyboard. As such it is very natural to select, move move, select, move, select... and so on. So in explorer I would always be able to do what I was doing there with no problem because on my single click I would have already deselected. (if i were an explorer keyboard user (less of them) by moving away, and if i were a typical mouse user by clicking).
That's why I think in this instance MC should behave differently than Explorer because it's a very different beast, one which is meant for keyboard use, and further more as you brilliantly pointed out on the splash screen, it's a tool for professionals, eg people who care (a lot) about productivity and see the huge advantage of a second here and there for activities done hundreds of times per day every day of the year for whole careers.
