Why? It's not an issue. Look at the update from Canon Rumors
I think he said virtually all other Canon bodies act the same way.
Actually no. He showed that only the 5D3 does. But it's not an issue (under his testing condition).
I can see how it "can" become an issue when one is shooting night-time landscapes and left the LCD on while metering. But that would only affect "auto/semi-auto exposure settings". If you're shooting in "M" mode in those situations, won't affect you.