A lot of the arguments on here e.g. World Wars, AIDS etc - all these big issues were tackled and were not seen again, or never had the same impact again in that generation's life time.
The Troubles were pretty long lasting and had an impact, mostly on Irish/Northern Irish people, and led to a huge rise in anti Irish rhetoric. I'm sadly old enough to remember (and be disgusted by) the No Blacks, No Dogs, No Irish stickers in windows.
Each generation has issues to cope with, and yes, the world has changed, negatively since 9/11, absolutely. But to dismiss such enormous issues from before 9/11 as tackled belittles what it was actually like at the time.
It's the millennials have it harder attitude I find difficult to get my head around. I'm apparently technically a millennial (by a couple of months), but when people speak of millennials I don't consider myself to be one.
Communication and the world becoming smaller because of the internet and communication between people across the world becoming easier than previous generations highlights things in a way that didn't happen before, yes.
But I find it hard to believe that millennials consider themselves to have had it harder than previous generations, and quite tactless too.