I think it is just the ups and downs of the service rather than a noticeable trend downhill
Coat - Never been offered in Y
Steamed towels - probably right but haven't noticed
Meal menu - most flights have a printed menu but the odd flight has missed out
Personalised greeting - I got one 3 years ago but none since
Food quality - Is this the western or Korean option? I found the Korean options are always the same in Y, to the point of being boring sometimes. Have not noticed any decline in the Korean options.
Friendliness of FAs - Goes up and down depending on the crews.
Toothbrushes - last trip in January had toothpaste in tubes, maybe a recent change.