Rotation, Rotation, Rotation

A question: what attribute was shared by the first crosswords published in The Times and The Telegraph, but not the first Guardian puzzle?

The answer is 180° rotational symmetry. It’s something that we take for granted, particularly in blocked puzzles, but why is it there, and would we care if it wasn’t?

I don’t think anyone is sure why it’s there, although it certainly simplifies grid construction (produce half the grid and the other half will look after itself) and checking, while the resulting layout is aesthetically pleasing. With the exception of the occasional barred puzzle, every crossword published in Britain will have at minimum 180° symmetry, with the odd one adding 90° symmetry on top of that. The main grid of every puzzle I’ve ever set has been symmetrical, and I’m a little put out when I see a barred puzzle where symmetry has been sacrificed to the demands of the theme. But why? The rules around unchecked letters (‘unches’) and disconnected sections of the grid (there were eight completely separate blocks in the first Telegraph puzzle, by the way) are there for reasons of fairness to the solver, but symmetry (except in skeleton or carte blanche puzzles, where the solver has to locate the blocks or bars themselves) has no effect of solvability.

I think the look of a puzzle is important, and I find a grid which is not symmetrical around a line or axis jarring, so my rating of an ‘offending’ puzzle will be downgraded accordingly. But I accept that this may be tantamount to criticizing Picasso’s artworks simply because they don’t look like paintings ought to. Views, anyone…?