I will grab the occasional file that really interests me, but lately since I've discovered sites like Flixer or streamvaults, I will just stream the shows and movies that I'm curious about but don't really feel the need to collect.
Disc rot is more probable on DVDs (and I mainly collect blurays).
I understand your point on collections and I'm an entropy guy too but I also appreciate a good collection of art for personal use during my lifetime, without compromises on quality/aviability, and maybe to left to someone in the future who will enjoy it after me. I'm kinda a minimalist for many things but not for art.