Still unsolved: And ultimately is there a way to prevent this from happening in the future?
Only use first party or authorized third party cards (Nyko, MadCatz). Don't remove or insert memory cards or controllers or reset or turn off the power while saving or loading saves. Make sure your cards and card slots are clean and free of dust, dirt, debris. That's about all you can do. If you still get corruption, it's possible your card or system is defective, and you need to replace it.

One thing, if you have installed that memory card hack onto your card to play backups or whatever, some of that data on the card will show up as corrupted data in the PS2's memory card screen. It's not, it's just the memory card screen doesn't know what that hack data is, so it assumes it's corrupt.