Dwarf Fortress is a game that requires a large time investment. You can easily play a fortress for tens of hours, and probably will.
But I think the fact that the game can just kill you semi-randomly so easily might turn out to be a real problem for the Steam version, and the wider audience it brings. Things like invasions, were-beast problems, the terrors below and tantrum spirals. There's of course an established way to circumvent that problem: Save scumming. And indeed, a significant part of the community would consider turning back time on fortress death by loading an old save, or at least keeping yourself the option open if the death was completely accidental, an important part of playing the game.
But new players probably wouldn't know about that option, and might get frustrated when they die from accidentally digging too deep or something similar. So my suggestion is this: Add a "load last save" button to the fortress death screen, along a "retire fortress" (or whatever it currently is) button, that just reloads the fortress from the existing save file. I think that would be an easy way to (in a lot of cases), give new players a chance to retry a difficult challenge, without having to build another fortress for five hours - time not everyone can or wants to spare.
Because the true soul of dwarf fortress is to have your hard work live on in an everchanging world. Not just having it disintegrate randomly because you accidentally left a difficult to see hole in some wall somewhere.