A good example would be the <meter> element which the spec specifically states:
The meter element also does not represent a scalar value of arbitrary range — for example, it would be wrong to use this to report a weight, or height, unless there is a known maximum value.
http://dev.w3.org/html5/spec/Overview.html#the-meter-element
This code is certainly not "bad code":
<section>
My height is 5 feet and 10 inches.
</section>
That's perfectly acceptable.I think marking up your height and weight and calling it better is dubious. Some would argue that the meter element itself is a bit dubious. I'm still not sure how I feel about it. A lot of the html5 elements are quite nice but you shouldn't go changing everything over just because it's new.