my 2 cents, to everybody complaining about the change, basically, think of it this way:
the world was announced as classical, so it should have had a +4 malus from the start
you came to the world, were positively surprised that it is not +4 but +7, as that speeds up progress
one would have expected a change to the right settings in the first week of the server
but everybody kept quiet and did not complain, and it slipped through the cracks of the developers
nevertheless, it is expected all along that the correction would come eventually
as always, those who took advantage of this temporary free lunch, good job
you ate the free lunch, you should be grateful
making an announcement in advance on when this free lunch ends - allows people that already got ahead - to prepare - so it may create an unfair advantage
so, of course, there can't be an advance announcement of the change, exactly like with the bubble bug on wcs 2015 or other similar incidents