Obituaries don't cost much. Papers do it more as a public service.
Maybe where you live. The "death notice" is the only thing the paper does free here. My grandmother's obit, which was fairly short and to the point, was over $500.
When my mother died, her mother (who, along with my grandfather, were the one's who raised me) simply said "well, at least she's out of her misery". My grandmother was one of the kindest, most forgiving people I ever met, but even she had her fill of my mother's crap.
Your right, we don't know the whole story, only what was in the obit. I'm sure the dad was at fault too (mine was). But, I wouldn't cast stones at the kids for venting some anger at the person who should have loved them, been there for them and so on. Because it's family and their mother, I can tell you from personal experience that it takes a LONG time to get over that kind of hurt. I tried for years to just "move on" and not let it bother me. Easier said than done. Wasn't until after my mother died that I was able to completely let it go.
