One, yes, Dwarf Fortress would probably be a lot more popular if the learning curve was less like standing at the bottom of the Grand Canyon looking up. A tutorial would be most welcome (but, see below).
Two, I think it’s important to make the distinction between Photoshop (think Dwarf Fortress / EVE) and MS Paint (think, I dunno, Bejeweled). The scope is very different. You need to learn one or two mechanics in a simple program (or game), while there are multi-semester college courses covering the huge list of features in the more complex program (or game).
Of particular note, the cost of doing a really good tutorial increases with the number of systems that need to be taught. Basically, the tradeoff is between doing a lot of features with a bad learning curve (and trusting that users will put in the work to learn even when it’s hard) or doing fewer features and having a really slick introduction. Having a ton of features, and a good tutorial that slowly introduces them all to the user, is incredibly costly.