Discs are being made more cheaply in Mexico these days.
I noticed this when I went to Canada last year. It really bothers me when they switch around and decide to do this in the middle of the series releases, then the packaging of the earlier seasons of the show are not very uniform looking. This bothers me because I have this thing about the shows having similar boxes and packaging all the way across the board. Yes, the truth is out, I'm a neat-nick.
So for the DVD sets, my only preference is that the packaging stays consistent. Sleeves don't bother me as I am very careful with the discs and have a scratch removing kit. What bothers me is this plan to save money by releasing these these two sided DVDs. That grates on my very last nerve. I would rather pay a little extra for single sided discs than to go the cheaper double sided disc route.
I think that CDs and DVDs can be easily scratched, but they are not as bad as vinyl records. Basically, as with anything, people just have to be careful with them.