I can't say it's especially bad.
It can disturb those trying to sleep if crew are constantly trotting through with trays etc. with risk of spillage and the noise of offering and thanks for drinks etc.
In F you have a call bell which you should be encouraged to use and water bottle, in J there's a water bottle and Raid the Larder and on both of those it's easy enough to ask for something in the galley.
In the economy cabins, there is usually a tray of pre-poured juice and water in the galley.
All seats have a call bell, though disturbance is probably minimised for those around you if you can get out of your seat and grab that drink yourself, or plan ahead and bring a a water bottle on board yourself (less easy at SIN, of course).
While can't say for certain, it may be that you nodded off when the trays came through (assuming you didn't stay awake the whole 22 hours!).
Too often I think people have lost the art (and possibly the courage) to actually ask for what they need, preferring to suffer and then bleat about it online, after the fact!