It's certainly much easier to get GM to use your animations, but I haven't tried anim8or, milkshape, or the animation aspect of Blender, so I can't say how the workspace feels.
And well, there's an animate-for-me button if you consider that it let's you tween between keyframes, as opposed to uploading a model for every frame if you used one of those other programs.
If you want to get animated models on GM, without using a DLL, I recommend using this.
In a sense, you could say that, but I was referring to the falsity of how simply having a handy program does not make you any better at something that your not good at. Not until you start practicing.
Yes it can tween, but if the poses you tween between don't look right, it still wont look right when you animated it in the game.