Please form an orderly queue

[Ruvanal]

So far, I've only found one of those out of the 50 or so quests I've completed.  You could kill Harvest Watchers to get Hops so that a dwarf up in the mountains would make you a barrel of beer.  You could do it over and over.

-Bolty

Yes, noted that too, but it seems like a bug to me.

Not really. It depends on which paths one ends up persuing through the quests. If you go through them by sticking primarily to the Westfall section then you encounter this quest there, do it and either sell or consume the reward. Then what would you do later on when another quest is asking you to aquire a bottle of that Thunderbrew if you could not repeat the quest when you need it. You would be stuck.

I view the Thunderbrew and the farmer that trades an apple for water to not really be quests but special types of vendors that do not take cash only specific trade items for their wares. It is just that they are set up using the games quest mechanics system for how they operate. Personnaly I would not mind seeing a couple dozen of these types of quest scattered around like that. A semi unique item that would not have a great value in return for some gathered items that the players may end up coming across anyways in their regualr adventuring. It is only when the reward item is very unique and much sought after that it will lead to situations as described for the other MMPGs.