Part of the factor may be people, like myself, who like the Wii exactly because you can turn it on, have fun instantly and enjoy it for 20 minutes for a break. I just don't have the hours and hours to get involved in a game like MGS. In 20 minutes I'd just be about getting into the story again.
I use it for 20 minutes of exercise in Wii Fit several times a week, otherwise unless I having a genuine down day (rare) or have company over, the best usage is when I get tired of writing and need to take a break , I may pick up MK and race around a few times or SSBB and practice my Princess Peach drop kick, or even Link Crossbow and relax and unwind for 20 minutes.
Does that mean I'm not a hardass hardcore, yea I reckon. Do I give a rat's ass - no not really