Well, let me explain that some more, because your comments show that you don't even know what you're talking about.
The 4 anime episodes will be released online. 2 have been shown, with two more to go. On top of that, The Final Flight of the Osiris is being shown with Dreamcatcher in theatres. That leaves 4 more Animatrix shorts to show us before, around, or after the third movie's release. So they couldn't release it any sooner, because we have a ways to go.
On top of that, it would only make sense to release them all on DVD after the trilogy is complete. Hell, they'll probably end up packaging them with a special edition of the third movie.