I disagree. Seeing animal villagers actually do stuff would add an whole new level of immersion to the game. They always talk about what they've done/are doing, but it's never shown.
Trying to argue that something is a "waste of pixels" when talking about a life-simulation game like Animal Crossing - which is pretty much 'pointless' in its entirety - is never going to get you anywhere.
The villagers don't have to, and probably shouldn't, actually catch fish/bugs from the 'pool' that we take them from. They could simply get fish from another 'pool' (but please make it believable, I remember the Bug Catching Contest in Pokemon HG/SS had other competitors catching and winning with Pokemon that didn't even appear in the grass on that day/time. lol) The villagers fishing in AC:GCN on the fish tournament day never hurt anything, so why in the world would it now? It just adds a simple layer of immersion that I think would benefit the experience of this game. Everybody always talks about how the new AC games lack charm (and make no mistake, I certainly agree), but then when somebody suggests something that would definitely add charm, they're pelted with "That's pointless, such a waste of pixels!". Make up your minds!
Just think about it, things that we argue cause charm, like the dump from the GCN version, the train from the GCN version, the separate post office from the GCN version - those are all what could easily be considered a "waste of pixels".