2. Minecraft modding is far more open.
Simply, Minecraft is more moddable. Dwarf Fortress does not have anything even remotely resembling programming. Interactions are turing complete, but as a system it's harder to use than brainfuck and nearly impossible to actually get output that's really meaningful to people. Minecraft uses Java, a fairly popular programming language that you can write whatever in, and it has wonderfully skilled programmers working to make it even easier for you.
This is really only because it's much easier to decompile Java bytecode back into Java (even if it's obfuscated) than it is to decompile machine code back into C++.
This is actually very true. Mojang promised a modding API so many times but they never delivered.
Minecraft is fun and it's a pretty good game, but the management on it is atrocious. Mojang's management is what happens when you give an unskilled amateur millions of dollars and tell him to head a studio. It's the sort of mess Toady has said he wants to avoid (not Minecraft specifically, but team work on a project). And the programmers who work on Minecraft are either average (at best), or stuck having to interface with bad legacy code from solo Notch days. If you think development is slow with Dwarf Fortress, Minecraft takes months for cosmetic changes like multicolored blocks.
You can argue the developer-side benefits of Java over C++ any day, and I'd probably agree with you on all counts (though both are antiquated and should not be treated as the standards of programming languages they are in so much of the industry). However, even the secondhand knowledge we, as potential fans of both games, have into either's development shows very clearly that as far as actual software creation and programming goes, Toady One is leagues ahead of the Minecraft team.
We should have more threads arguing the meta of Minecraft vs Dwarf Fortress. The "which game would be most likely to make a modern computer scientist cry" competition.