Another reason could just be the fact that USB loading sucks, the compat is low and when a game does work it's takes an age to load and all games that normally read from the disc mid game will lag mid game
P.S. sounds like the drive is now dead
Do you get any clicking sounds from the drive now?
Oh yeah I have plenty of games stored compressed on DVD+R's there will be some that are rather small compressed so you can sometimes get a few on there, though DVD+R or any disc media is prone to scratching and obtaining various marks that can make them unreadable, even storing them in a place that light/heat can get to them will warp there shape eventually
If you go for the HDD backup method it would be better to have 2 seperate HDD's both having the same backups on em, then if one dies you just get another and back the surviving HDD up onto the new drive
Recently I lost a 1TB drive and a 300GB drive within the same month
... gutted but restored most of it back now, one just got corrupt and has reading issues... can't format it successfully
the other one the board had died on it, so all it does is click, to replace the board on my 300GB when I looked actually cost almost the same as it did to replace it with a 2TB drive, so it wasn't worth the money plus I had to take a chip off the old borad and solder it onto a new in the hope that the chip was not fried