That number alone is useless and greatly favors UIs that are messy.
True enough, I oversimplified it. The information presented also needs to be relevant.
A really good UI requires a small number of inputs where the inputs can be learned or inferred easily. From a presentation standpoint, it should be extremely easy to switch information on and off in a rapid fashion without taking up gobs of the possible screen space.
That said, it's virtually impossible to claim a UI is good if it takes a large number of steps to accomplish basic tasks, especially if there is delay between inputs to the extent that the user can make an input and have the program not register it as having ever existed.
What's funny about Civ V UI however is that it fails invirtually every single UI consideration. It's slow as all get-out, makes navigating to collect more information a pain, requires a ton of unnecessary inputs, lacks any form of readily available customization, and for all that it gives up it doesn't even manage to be more intuitive than previous iterations. It's pathetic. This is one of those areas I actually agree with Sulla; why use up so much space and then give comically tiny buttons on things like queue?
Unlike TMIT, I am not a speed civver and an extra click or two does not bother me so long as this follows naturally from the structure of the interface.
No matter what, if something requires an extra click or two, there better be a **** good reason to require an extra click or two. Reducing what would otherwise be too much clutter is valid. Accomplishing nothing at all + adding steps is not. Compare queuing a unit in a city in IV and V:
IV:
Click on city, hold shift, click unit
V:
Click on city, click on city again, press excape, click show queue, use a tiny button to add units
Really? Why? What did that add? Nothing. Why did they do it? Only to add a heaping helping of "fail"

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