I definitely know more younger people interested in discussing animal rights.
Actually, whenever any adults hear that I'm vegetarian they usually feel the need to go on some long-winded rant about how vegetarianism is wrong.
TBH, I think this may have two main driving factors..
1. THe information is quite easily accessible about animal cruelty and such. We a raised in a world where there a documentaries like that on four corners and questions being asked about animal cruelty. People of past generations were raised with a focus on different values and attitudes.
2. Much older people, like my grandparents, come from places where they lived on farms and used to kill their own animals. They were desensitised to this process and furthermore tend to believe that all animals are treated like this. On small farms with farmers like they were, they are unaware of commercial farms. (My grandparents are examples of these people).
I know those are generalisations, but they hold true for most of the people I know.