Meh. I don't want the way my character looks to determine what I can and cannot do. This is fantasy anyway. In fantasy, weak looking characters can be really strong, while big characters can be weak. It isn't as black and white as in real life.
Depends what fantasy you read. In David Gemmell's books the law of physics still pretty much apply. Just exaggerated. However I agree that some computer games don't e.g. Cloud and his sword.
TES I feel follows more realism, in Oblivion every character body was ripped to shreds, they all looked like Olympians. Most body builders aren't strong, they go for size and look. At competition weight they are at their weakest. You want to look at http://www.google.co.uk/imgres?imgurl=http://www.citylife.co.uk/img/13491/21929_carlos_accosta_as_apollo_image_courtesy_of_angela_taylor.jpg&imgrefurl=http://www.sodahead.com/entertainment/what-do-you-call-male-ballerinas/question-1565537/&h=600&w=402&sz=136&tbnid=TK4q9GIFv826kM:&tbnh=274&tbnw=184&prev=/search%3Fq%3Dmale%2Bballet%2Bdancers%26tbm%3Disch%26tbo%3Du&zoom=1&q=male+ballet+dancers&hl=en&usg=__3stEbqYssZBBTNAZ7tKiKddb88E=&sa=X&ei=bcHoTe-fBIfLsgbexsnnCg&sqi=2&ved=0CC4Q9QEwAg and rugby players for your realistic fantasy body model. Not http://www.google.co.uk/imgres?imgurl=http://images.mylot.com/userImages/images/postphotos/1612342.jpg&imgrefurl=http://www.mylot.com/w/photokeywords/ronnie%2Bcoleman.aspx&usg=__ewAgNYUYGNVwNmHl1hdTIv-U3Pk=&h=336&w=479&sz=51&hl=en&start=0&zoom=1&tbnid=FqZ-UIuQikdoIM:&tbnh=111&tbnw=148&ei=-sHoTdmBKMnbtAbOhuyACQ&prev=/search%3Fq%3Dronnie%2Bcoleman%26um%3D1%26hl%3Den%26sa%3DN%26biw%3D1406%26bih%3D417%26tbm%3Disch&um=1&itbs=1&iact=hc&vpx=320&vpy=113&dur=753&hovh=188&hovw=268&tx=157&ty=106&page=1&ndsp=20&ved=1t:429,r:2,s:0
However, that being said I dont think OP should be the case becuase it limits people's options in character design. If you want to play this way
you can that's the beauty of TES.
Even if it makes no sense that a skinny little boy that looks like a girl can lift and swing a giant sword all day long.