I have been a long-time vocal critic of MTG, and for a number of reasons. This post serves as a summary. Review for version: 5.5.0
The biggest problem, tho, is that MTG just "feels" incomplete. In essence, MTG is a Big Empty Sandbox that Jim-Stephanie Sterling talked about on the Jimquisition. Meaning, the world is large, but the number of different things you can do is very small. It thus feels "empty".
So what can you do? You can explore the world, but the biomes don't offer special items that advance the game (except food, maybe). You can go mining, but it's easy to get to the best ore, the diamond ore. You can farm blocks and build, and you can farm wheat and cotton. And this is ... mostly it, apart from some smaller features. Needless to say, a new player will have explored all the major features fast. Not being able to do various different things is the death for any sandbox.
Thus, you run out of new things to do in MTG fast. Once you get the best tools, farmed some resources, built some things, that's all the game offers, basically. MTG is fine if you really only care about raw creative building. The selection of blocks is fine, and people did build amazing things in MTG.
But IMHO, the standalone MTG is completely uninteresting as a game. It is, however, extensively used for servers, but in a heavily modded form. As a basis for servers to add mods on, MTG has done its job well. As a basis for modders, MTG does an OK job.
But most players want more than just a raw sandbox. MTG does not deserve its special status as a default game and should therefore lose it. That MTG is still the default game is the single-most damaging thing to the whole community, because it makes such a bad first impression.
Thankfully, development focus has mostly moved away, as MTG is currently in "maintenance/bugfix-only" phase.
Full disclosure: I did contribute some smaller features and bugfixes in the past and also a translation. But not the big stuff.
Well first off I'm more of a type that would like MTG to be kept, becuase:
1. There are already so many mods made for MTG
2. I definantly agree it can get boring pretty quickly, but, I think we need to focus on getting people to know you can easily add mods, so maybe adding little tutorial sorta pointer things, that give you a heads up on adding mods, or trying out new games.
3. I'm not one of them, but there are people who don't like mobs or don't like hunger etc. which is not included in MTG, so people like that.
4. And what's the solution? I'm open to peoples ideas, but I'm not a huge fan of the idea where the only game is Dev Test, and it tells you to download a playable game.
So like I said that's my opinoin, and I'm open to others ideas, of how this "problem" could be "fixed"