I'm glad the way it is. If people are'nt dumbasses and don't swap mempaks while the game is trying to write or read to it, then there's no problem. I don't think the game is constantly pulling or writing information to the mpk, only at certain moments, i.e. the end of level and it usually tells you as well.
I mean people on the real console could physically change mpks during the game and so long as it was'nt trying to write to it, no harm done. If people are stupid and pull the mpk at a saving or reading moment, then they deserve what they get. But the rest of us should not be punished for the acts of people who are'nt running on all cylinders. If people in the real world can do this, I think we should too.
And even if you DID get rid of this freedom, people could always switch to the rumble pak during a mpk write and boom there you go, possible corrupted mpk. Or they could close the emulator during a write. I mean there's a dozen ways they could corrupt mpks. We can't stop them.
About 30% of my games need a mpk. So I keep my rumble pak plugged in since 90% of the games have rumble. If the mpk system did not let you change during gameplay then I would have to:
1. Change from rumble to mpk and then pick the mpk for the game I'm going to use and save.
2. Boot game
3. When prompted, open dialogue and select rumble pak and use
4. When prompted, toggle with shortcut keys to plug back in mpk to save
5. Then when done with game, close rom and then open up dialogue, select rumble and save to get ready for next time
As opposed to current system:
1. Boot game, when prompted for mpk, open up dialogue and select the right mpk for this game and click *USE*
2. When prompted, toggle shortcut keys for the rumble pak
3. At end of level, shortcut keys to save to mpk and the shortcut back to rumble
4. When done with game, simple close and that's it.
This is how its been forever so I don't think it needs changing. Even the easiest system is kinda a pain in the ass (especially when compared to PSX-memcards separate from rumble system). So I think it fine the way it is. It's more convenient and gives people more freedom with how it is.