I think there is an IATA rule that all airlines have to offer full fare Y J F so often they are priced to make it obvious there are better deals than full fare, by making the small fee plus the lower fare much less than a full fare old fashioned "Y" ticket. Making that even more than mostly refundable J (e.g in D or I).

The bottom line is that it's really not relevant - your HKD1,800 fee - if the alternative is a fare that lacks that fee but costs HKD30,000 more.