Time symmetry is probably not a big selling point of the classical formulation of the MWI. What with all those worlds in the future that don't exist in the past.

OK - no information is created or destroyed - so it's technically reversible - but that's not quite the same thing as temporal symmetry.

It would be better if it were formulated so there were lots of worlds in the past too. You don't lose anything that way - AFAICS.