> This is why table-based layout fell out of favor.
No. No. No. No it is not.
Table-based layout didn't fall out of favor because table cells didn't include enough semantic layout information. It fell out of favor because tables are for tabular data, not layout, and layouts that used them therefore created negative consequences in all kinds of situations where the UA expected a table to actually be a table, such as when accessed by a vision-impaired person using a screen reader.
From this perspective a layout using DIVs is always better than a table-based layout, even if the classes and IDs of the DIVs are named presentationally rather than semantically, because DIVs at least are neutral -- they don't carry the weight of a bunch of semantics that are irrelevant or at cross-purposes to what you're trying to achieve.
You are correct that a DIV that's named "left-column" is marginally better than a DIV that's named "span4", if only because of the additional semantic information included in the "left-column" name. But either DIV is far, far better than any table-based layout.