. . . can it be changed back to how it used to work?
I investigated to see whether it could be changed back, but all I did was create a mystery.
I ran an EasyFind search to see see if there was any toggle-type command to turn instant eject on and off.
Three of the files it hauled up are hdiejectd.plist, hdiejectd and Eject.menu. The rest are png files. I could open the plist with TextEdit, but that showed nothing except a "true" that presumably could be changed to "false." But changing it to false probably would nuke the eject key. So with TextEdit, I opened hdiejectd, then Eject.menu.
Neither showed anything obvious, so I closed them. But now I have a brand-new disk-eject icon in the menu bar. Clicking it opens and closes the disk tray whether there is a disk in it or not. But I haven't a clue as to why this icon appeared.
It resembles the icon that can be added to a Finder window bar, but that icon works only if there is a disk in the tray. I can move the menu-bar-eject icon if I hold down the Command key, so I could pull it onto the desktop to get rid of it, but I'd prefer to leave it.
I just don't know how it got there and how to put it back if I yank it.
Deepening the mystery, TextEdit won't open the two files anymore from EasyFind.
From Eject.menu in EasyFind, the only choice to open it is SystemUIServer (default). Nothing happens. If I choose Reveal in Finder, the choice is SystemUIServer (default) again. TextEdit says "File not supported."
Terminal and X11 are the only choices to open the other one, hdiejectd. I can open it with TextEdit if I choose "Reveal in Finder" and open it from there, and it shows almost-English in a few places. Terminal says "permission denied." I have X11 installed, but nothing happens when I choose it.
What am I missing that might be blatently obvious? Short of that, how did I put the icon up there? All Apple's Help says is:
Click the Eject icon in your menu bar, if there is one.