Nothing against these games, but something really bugs me about them. Ethics aside, if I wanted to play Minecraft for free, why would I decide to play these instead of just pirating a copy of Minecraft? (I only mention piracy because a simple "why not Minecraft" question would be answered by "it's free". I would like an alternate answer than cost.)
I've played a couple of the Minetest and Freeminer games that you've mentioned before, but they just felt like less-refined versions of Minecraft to be honest. All of the different features included, and the ones that they say they're working on are all features already implemented in Minecraft. I've seen enough people get upset at calling them just Minecraft clones, but to be completely fair, they don't seem to be doing much to try and go their own direction. It seems as though they're just staying barely separate enough to avoid lawsuits, like not including Creepers for example.
Like Koh said, why is it that all of these games are just drawing features from Minecraft instead of other voxel games like Trove or Cube World. Hell, Cube World's pretty much dead as-is, and it looked like it would have been a ton of fun. I'd love a game with the village, quest system, and combat mechanics of Cube World alongside the build-anything focus of Minecraft. Honestly, if I had the know-how on how to program something like that, I'd probably try to do it. Stuff like weapon creation working similar to Gummi Ship building in Kingdom Hearts, tons of unique enemies instead of just four or five, it would be a lot more unique than just another version of Minecraft.
Still, I'm not trying to hate on these games, so I'm honestly asking. Maybe I didn't play long enough to see the differences. What do these games bring to the table that Minecraft doesn't, other than the fact that it's a free alternative?