Yeah, I didn't have much problem with the learning curve either, I just looked through a bit of the beginning section on the first fortress. Enough that I knew how to pause and look at things, which I did for a good while until I knew what things were. I've played a lot of strategy and sim-type games, and a number of roguelikes and such, and ancient commodore 64 games with keyboard-only controls, and lack of in-game tutorials, and so on, so getting used to the graphics and interface wasn't hard.
The problem is, that seems to be nearly all of the challenge so far, learning the graphics and interface, after that, it's fairly easy (well, and figuring out what you need, in order to build what objects, and what it is that your dwarves actually need, and learning the world in general, etc.). The learning curve is a brick wall, but once you get over it, you can slide back down the other side. It probably helped that looking at it, and with the slogan "losing is fun", I was expecting something of nethack-level difficulty(and that's still what I'd like to see), so I built my first fort someplace that looked safe and remote, and focused on food, water, and defenses.
Once you've learned how things work though, it becomes easy to grow huge quantities of food, make tons of drink, keep everyone ecstatic, with a tiny amount of area, and just a handful of people. Making your fortress completely-self sustaining is extremely easy, and making it completely impenetrable is easy too. No need to worry about keeping your dwarves warm in the middle of a tundra in winter, or even about them wondering around outside naked, or walking around a scorching desert, unless you've modified the temperatures up to 1000 or something like that.(which I have done, and which is interesting, but doesn't really effect you much once you're settled in underground, and makes defending from attacks even easier than it already is). Let alone worries about water or rain, when you don't even need the stuff. Doors, walls, channels, bridges, heck even just the remove ramps command in the right location, any one of them alone can practically make an impenetrable fortress(along with, properly applied: floors, hatches, grates, bars, floodgates, removed stairs, obsidian, mining cave-ins, edges of workshops, pumps, windows, statues, even cultivating a tree to grow in the right place.). Let alone traps, which can be built in huge quantities and kill things easily, and more elaborate defenses. And even without that, how powerful just a handful of military can get with a bit of quick training. And how quickly weapons and armor, and other crafts can be made to equip a huge number of them by just a single person, not to mention how quickly everything can be made, built, dug out, etc, even making huge-scale defenses, which you don't need, takes just a small amount of time and resources to build. And how easily you could make hugely expensive things to buy anything you need, if you couldn't already make it all quickly enough.
Making the beginning learning easier would be nice, and could be helped out a lot with things like tutorials, a more useful manual, better information provided when looking at an object, etc. But when you get past that, what would really be nice, would be to bring up the difficulty level dramatically, make it a difficulty curve, rather than a difficulty hump. Give it a bit of effort even surviving in a calm temperate area, and a long time and a lot of dwarfpower to build or carve out a village, let alone a fortress, rather than just being able to send a single miner out, and have them finished in a season or something. And much more of a challenge still building somewhere with a less hospitable climate, or more dangerous creatures, closer to a goblin tower, etc. I've seen some complaints that things like this would make it too hard for people learning things at the beginning, but add in tutorials, or an easy mode that disables some of those things, that people can learn in before they move on to the real game.