I object to the across the board, frequently negative, characterizations of "millennials" for a bunch of reasons, but they fall largely into three baskets.
In no particular order:
Firstly, I object to the whole damn generation thing on statistical grounds. See here.
Secondly, It's easy to find people who have negative traits or embody things you dislike or distain. You can probably find those characteristics in people of any age, and people with those characteristics at any point in historical time. Is it about the person or about the group? Do this trait appear more frequently in a given group, defined by some other group characteristic?
And thirdly, which is really an extension of secondly, when someone does or says something you don't like, it's easy to paint with a broad brush and attribute it to their group membership. It's ok to do that with age groups (both young and old) these days, but we've sort of come to our senses about doing this when the group is race, religions, gender, orientation, and maybe a few more. (Note, this is different from Political Party Membership, which is much more of an active choice, but still, one needs to stop and think).
Now, maybe the thing they said or did or didn't do or didn't say that was objectionable to you was because of their group membership. But maybe they're just an asshole. When you start making group generalizations, you run the risk of characterizing people who you might like, who you might find as a friend or an ally, who might help catalyze your growth, as being just like the asshole.
So why write this now? There was a comment on this blog, and it was considered rude and wrong and horrible by many people on the tweets. I'm not going to censor the comment, nor unfollow because of some very strong tweets. The discussion has had many good points that have made me think, and made me take some actions to support and defend young people, where I have the power to do so. But I'm not interested in that broad brush that says "discount all the oldies". Discount me, because I'm ignorant or selfish or dress inappropriately. Unfollow me, because I'm a jerk, or insensitive or I like coffee too much. But because I'm old? It won't matter to me, but it might matter to you.
My mother, the gerontologist, was a life long democrat. She worked for Adlai Stevenson (ok, go read the link, I've made it easy for you) in the 50s and Civil Rights in the 60s. When Ronald Regan ran for office, there was a lot of talk about his not being able, because he was so old. She was furiously opposed to this line of thinking. "Criticize him because he's wrong. Because his policies are selfish. Because he's not too smart. But leave his age out of it. What if the guy you really liked for policy reasons was that old?".