css layout should be symmetrical

I'm beginning to think that css layout should be totally and completely
symmetrical. 
 
That's to say that, for example, it should be possible to have <th>s at top,
left, right and bottom of a table - or at least two dimensions
simultaneously. I just finished making a table that had a row at the top and
a column at the left that were both structurally headers, and I'm sure I'm
not alone. Colgroups are not the same thing - more like a parallel of tbody.
 
Similarly, it should be as easy (and also take a parallel or identical set
of commands) to centre a block horizontally as vertically. I think it was
pointed out in the "How is it possible to devise such a feeble system"
thread that this is not currently the case.
 
Part of the reason for this, beside convenience, is to fully support
languages that are read in different directions than English. The fact that
inline elements line up from right-to-left while block elements line up from
top-to-bottom clearly demonstrates a bias in favour of languages that read
left-to-right and top-to-bottom.