Well, let me put it this way. Dwarf Fortress is different. It does not follow a whole lot of what people are used to in games, it does not appeal to a lot of people. The Ascii takes a while to get used to, and it doesn't play nice with the user. When I first saw it, I thought it was stupid, sure as hell is obtuse. The difference is though, that I had more to go on than "This is a game, here is what you can do", I had stories of what's been done in the game.
Secondly, Dwarf Fortress is different. For some people, it just might be that it's everything they think shouldn't go in a game. Some people are just not going to enjoy it, ever. Some people don't have the time to spend a week, at least, to learn the basics of a game. Some people do not want to dig through a wiki to find out why everything is on fire.
Thirdly, people are different, and have plenty of different tastes. Somewhere out there there is a person who thinks we are dumb because we can't tell Louis Vuitton from Chanel. There are others who think that everyone should know what a three act setup is. Or that you ought to tell a soup spoon apart from a table spoon. At some point though, you have to realize, these are terrible reasons for insulting someone's intelligence.
So yes, they have the right to hate the game for what it is. That's fine. They might not be willing to invest time and effort into learning a game when they can be having fun. That's fine too. It just might be best to live and let live.