DAKOTA,
I don't think you overreacted. I think your reaction was a normal one. Unfortunately, many, many people are rude these days, IMHO. I concur with those who say that people are often disorganzied, that these responsibilites--if they're considered that--are often left to others. I also concur with FJL; I believe that hearing of a death makes many people very uncomfortable--it's too close to home--and they sometimes experience some emotional paralysis as a result. And, yes, when an older person dies, even if it's not a parent, people can be quite callous. After the death of someone I was close to, one friend of mine said to me, "Well, he was old, wasn't he?" (No, he wasn't.)
It's often difficult to know what to say at these times. And sometimes, too, people are having so much difficulty coping that they really don't want to talk about it, particularly at work. When my dad died, I appreciated the words of condolence, but no, I didn't want to talk about it. I needed time alone.