I think that it's simply considerably warmer 6 weeks before
the solstice than 6 weeks after it. 6 weeks after is early
February which is still the depths of winter. No point in
having the lighter evenings to make them more 'useable' if
it's too cold in practice to make much use of the extra
daylight.
Col

At least if there is the 'extra' daylight it's up to individuals
to decide for themselves whether or not the 'extra' hour is
'useable' or not, rather than some sedentary office-wallah in
deepest Whitehall or Greenwich!

Just think of the extra hour's skiing one could get in if there
were lighter evenings in February. Or if it's cold enough,
skating after work on the local pond. Great!

Anne