Dwarf Fortress is possibly one of the only freeware games I saw that I fully believe should be published
I have no problems with it going mainstream
Look at your examples: X-com, Simcity, and civilisation... In all of those you STILL have the originals.
Though seeing as Dwarf Fortress is likely never to be completed (it seems to be one of those games made to be in production basically forever) and a mainstream version would not only be completed but would look pretty... I can't argue against it.
So Toady could possibly get a ability to create his version of Dwarf Fortress even while the main stream version was being made... so he would never have to worry about donations and thus not ONLY would you get the fully completed mainstream version... but you would finally start to get the completed NORMAL version. (Heck Toady could probably hire some people to do some optimisation)
And ALL the community would have to deal with is annoying fanboys who would eventually go away and stick with the Mainstream boards.
"you mustn't be discouraged by trial and error and losing many times and most of all, you need to be creative"
-Dwarf Fortress like many Freeware games does this to a fault. Requiring the player to know spoiler information or do activities to the point of being obsessive in order to make it work.
--a large portion of people who support such mechanics are usually people who like Bragging rights... those are some of the "Elitists" most a "Hey I can beat a game that you can't because I know things you do not".
---I have nothing wrong with difficulty... but I do have something wrong with needing information hoarding to play successfully. (though Dwarf fortress isnt as bad as other games where in order to win you basically need to know a sheet the size of your arm full of information you wouldn't normally know in order to win). Though Dwarf Fort does this less then a lot of games I know it still has "Ohh you didn't know this? Too bad you lose" situations and you probably played the game for hours on end to get to this point. It is kinda the difference between "difficulty" and "Cheapness"
----Though mind you that from what I read... Toady is trying to fix this problem.
-----I mean just look at your graph... it isn't "Skill required" it is knowledge. (I am soo happy I didn't try to learn the game on my own... Id have stopped playing the game quickly...).