Not to contradict your general point, but the i5/i7 MBPs from early 2011 onwards support 16GB total - it was just not a config Apple sold for some reason.
Apple continues to disappoint. This kills any desire I had to buy one of these. If I can't keep upgrading it over the next few years as I need it, what is the point of buying this over an Air?
The point in buying it over the air remains: 15", retina, etc.
This is not something to be mad about. If you buy the maxed out 16GB, well, it's maxed out anyway.
If you buy the 8Gb, it's a compromise you make. You'll live with the 8GB, or sell the laptop to upgrade. It's worth the trade-off (small size, etc.)