I dont think DF has a very steep learning curve.
I think there are lots of simulators and strategy games (and I dont mean "real time "strategies""..) that are much more difficult to learn and become good at.
Did you learn how to play the game by yourself, or did you require help from the wiki? Did you know how to do anything beyond random-button-press when you started, unless you looked at the wiki, like most of us did still do? Most other games are basically clones of other games, and as such are fairly easy (and intuative!) to figure out. No, DF has one of the most insane learning curves ever.
I figured most of the UI and basic mechanics out before finding wiki and Dwarf Therapist. And yeah,
most of the games truly are just each others clones aiming for the lowest divider and mass sales. But I dont that gaming wise DF is too difficult, if one doesnt want it to be (or make some hilarious, dwarf-hurting mistake, usually involving a needlessly complex construction or two, water, magma and/or gaged megafauna
).
EDIT: For example I dont think anyone who plays DF thinks that in a game, graphics are the most important part, right behind it following action and ease of getting into it. I dont, either. And I also like games that dont think the player is either a 11-year old ADHD coke addict or in need of a lobotomy... Few are the games where the player actually needs other than quick reflexes, that arent simple and easy, that have players. DF is one of those.