My shortcut icons have lost their original icon shortcut picture and have defaulted to the same simple icon picture.

That happened to me and I have seen other users post about it since the update to iOS 8. I don't know why it happened but it happened to me a second time after I restored my iPad to factory settings and then restored my backup.

There are several things that I did that worked and you can try as well to fix it. most of the time, launching the website again and then closing it, brought back the normal icon for me. A couple of shortcuts would not come back, so I recreated them.

1. Open the website with the shortcut, then close it and see if the icon comes back.
2. Restart the iPad.
3. Reset the iPad by holding down on the sleep and home button at the same time until the Apple logo appears on the screen.
4. Navigate back to that website and create a new shortcut and delete the old one.
5. Reset all settings. Settings>General>Reset>Reset all settings. No data will be lost, but most of your preferred device settings will have to be entered again.

I'd also try just deleting the shortcuts and adding them back.