It appears that strong winds predicted for 5 & 6 January coupled with a long flight plan, have made Malaysia stop accepting hold baggage to Paris and Amsterdam.
The prohibition to London has been lifted.
Their press release says:
Normal baggage allowance on Malaysia Airlines’ flights to London, operated by the A380 aircraft, has been restored with immediate effect.
Baggage limitations however, still apply for flights to Amsterdam and Paris on 5-6 January 2016.
Please refer to our travel advisory section for further updates. Next update expected at 0100GMT/0900 Malaysian local time.