It ain't really a problem. It's somehow a great strategy so your opponents won't know what you're building.
Consider it to be training for the Warp Gate, when it is in Warp Gate mode, even if you did know when it was producing something, you wouldn't know where. I am sure Blizzard has taken the building's animations into account, and have been considering it in testing. If they find a real need to tell players when it is active, then they'll add the appropriate animations.
...Atleast you your Protoss opponent is creating Zealots and Dragoons but you don't see they build mens anyway until you get to their base
about half of the protoss buildings didnt show you if they are doing anything or not and it is the same thing with all the zergs buildings.
there are so many factors that go into that process, its very precise, even the amount of buildings the protoss require to upgrade themselves can be seen as a waste but its also a factor in making the game balanced, between the races.
That's because the zerg building didn't produce anything. : :stupid: But it might be because of the balance, I don't know. It doesn't matter that much anyway. Just assume they are always building, because that's what you should do anyways.
what i mean is in the terran case the buildings still show some kind of animation even when the building is just researching something, but in the zergs cause all the buildings dont show a different animation when they are bringing about an evolution upgrade.