Simplicity, very quick to for certain use cases. I use it all the time to time-align MIDI tracks to use them with pianojacq.com so that the scores look good and are beat perfect.
If it is just specifically MIDI editing that you need, a DAW can often be overkill. And when it is only MIDI editing, the (free/relatively updated) options are fewer. Sekaiju being my preferred tool, but there is also Aria Maestosa which seems less featured, but shows music notation and guitar tabs.
If you use it frequently: try to stay away from full screen, even just a hair under full screen in width and height seems to make it more stable, and try not to zoom in too far. Those two things alone seem to allow me to work much longer between crashes.
Thanks. I am back on Windows these days and had to set the hi-dpi display on my old Dell to 1080 in order to read anything in MIDI Editor.
But my use was just temporary to solve a specific problem.
I used Musescore to write the final composition for my beginning music theory class at community college and wanted to load the MIDI into my QY700.
But Musescore was adding an A3 metronome to its output when playing on all four channels and was setting all velocities to 0. So the recordings on the QY700 would require a lot of manual editing.
Then Live Lite did not work the way that would be sensible (upper tiers do of course). Plus, deliberate dawlwessness means I am not very experienced with it.
Anyway, I downloaded MIDI Editor and got the MIDI files into the QY700. Then once the pressure of the problem was gone, I had a play with Live Lite and figured out how I can write MIDI from it to the QY700 so I may not need MIDI Editor in near future workflows.