While it's an interesting idea, the ultimate reason why it's put into the upper left corner is a basic of UI design. Here are some basic facts:
- The center of the screen is the most comfortable point the eye can watch.
- It is more comfortable for the eye to move to the left, right and down. To a lesser degree, it's comfortable for the eye to move up. Diagonals provide more stress, the farther that your eye moves.
- It's important that when your eye is observing the interface at a natural point (the center) that all the information in the most comfortable regions (left/right/down) is as consistent as possible. (This is why the left/right edges are typically clear and there is typically a "dip" below the center of a screen) To define "consistent", it should nearly the same information.. in other words regarding SC, "the battlefield". (However, if you want to create a claustraphobic interface as part of the identity, you can intrude upon this diamond.. think Airplane sims and how the bottom center "peak upwards)
- Anything outside of the natural playing area is something that typically involves mental choice to look at. For this reason, if there are parts of the interface that you wish to be constantly aware of, it should intrude upon the nautral vision of the eyes. BUT if you have information that involves a choice, it should be in a place that involves choice. It activates the same parts of the brain. (This is ALSO why airplane sims put the specific instruments you want to watch into the diamond.. you "react" to those.)
There are more than that, but these are the only ones off the top of my mind that are relevant to this suggestion. For these points alone, and understanding the point of the UI, I feel that it should stay in the upper right. While the information it provides creates a "pro" of watching minimaps more (which should be a choice... I think that the cons it provides to the interface can be more distractive.
Oh yeah, I forgot a final point:
5. Right handed people naturally look right more than left when interacting with video games. The majority of the playerbase is right handed. Combine this along with the mentality that it's easier to view upward when "contemplating choices or thinking" (I dare you to put your hand to your chin and go "Hmmm". You will feel your eyes drift upward) upper right is the most notable point to put information regarding mental choices. Since "down" is more natural, it's to provide instinctive reaction points to look at. This is why the minimap on RTS is typically on the bottom if it's a "reactive" style game... and put in the upper quadrants if it's a game that involves mentally making a choice regarding it (Such as WoW by default)
I learned all of these little nuances and more when assisting veteran designers create a UI in one of my contracts. It's pretty interesting stuff... it also explains why some interfaces "feel wrong" for some people and others "feel right".