AE needs to communicate when it's trying to update the frame
AE will frequently show a blank comp window (upon opening a project), or not update the comp window and give no indication that its reading from disk or working to render the frame. If AE isn't showing me the actual current contents of my comp, I need AE to communicate that. I need to see a progress bar that says "Yes I know the comp window is blank, but i'm working on it." or "You're not seeing the text layer you just created because i'm still rendering it."
If you don't show me a progress bar while AE is updating a frame, you're just saying "Yes that text layer is there, but you can't see it because you're crazy." It inspires self-doubt in the user and/or distrust of AfterEffects.