When I was growing up my family ate dinner together. We all sat down around the table and it was nice.
Sadly, I don't think that happens as frequently these days, at least, not at my house, and I think part of the reason - aside from my absentmindedness and slackness - is technology. You can yell out to your kids that their dinner is getting cold, and they'll think, "So what, I'll put it in the microwave later." Or they'll just get out some instant soup or prepackaged dinner, nuke it, and they're set. Unless you run a tight ship, any kid who knows how to work a microwave can prepare his or her own dinner on his or her own schedule. I know it may not be very nutritious, but I don't think that makes much difference to a lot of children.
In addition to food technology, there is also entertainment technology. Not only is there television, as there was when I was a kid (and that was hard enough on family dinnertimes), now there are also video and computer games. It used to be that talking at dinner kind of was the entertainment, but nowadays it's hard for mere talking to compete.
You can't rely on hunger or the fun of being together anymore. I think that having family meals now means additional pressure on parents to make them a requirement. Get a bit slack and you loose it.