Did they run out of time? will it be like this in d3?

Whether Diablo II did it purposefully or not we very much like the feeling of accelerating toward the end of the game with gradually shorter acts as you go. I can't yet speak for actual play time vs. what Diablo II provided, although we aimed to hit the same amount of time, I think we're quite a bit over. In any case, we want the player to accelerate toward the final conclusion, so the last act will certainly be the shortest.