The thing I hate most about bootstrap 3 is changing the class names of the grid. "span3" and "offset1" were much better than "col-lg-3" and "col-offset-1".

Seriously... there are several places in the docs (and I often do this myself) where a non-grid-related element uses a "span2" or whatever to float itself left and size itself equal to a 2-width column. Example: the input field for a search box. When input-medium/small/mini/large/xlarge doesn't cut it, or just because you want something to fit in a column.

So now we're gonna have "col-lg-2" etc plastered throughout our html? I don't see that as an improvement. The elements that get used the most should have simple names... that's what made bootstrap great as it was a common-sense standard for lots of common html/css techniques. "hide" for display:none, "muted" for color:#999, etc.