Reason for the decision has been blamed on numerous factors, including high fuel prices, high taxes and weakening demand in Europe, which makes it difficult for them to be able to offer low fares!

http://www.bbc.co.uk/news/business-16526235

Also, China Airlines have announced that they are stopping their flights to/from London-Heathrow; again rising oil prices and passenger load factors have been cited as two of the reasons for the move.

http://www.businesstraveller.com/asia-pacific/news/china-airlines-direct-taipei-london-service-und

According to several business news in the Asian region, the new EU Emissions Trading Scheme (ETS) is the main culprit why some Asian carriers drooping Euro routes or seriously reconsider Euro routes.

China carriers (with the backing of Chinese Government) already stated they will boycott the new rules. How they boycotted are still unknown.