I've said this 20 times over, if you don't like it, don't use it. People play how they choose to play, if you think its not a good idea, then dont use it. As for the people who like the idea, thell use it to their advantage. It's not under your controll as to if it ruins the game or not, its just the way that you like to play it.
I could care less about the fishing. I love the idea of having the fish around though. It would be reason alone to make an underwater structure. Watch the fish swimming by... would be good times, indeed. It'd also make the fishing pole useful. Not that I'd ever probably use it myself, but I find the unusable items (eggs, fishing pole, milk) to be annoying. Why be there for nothing? Even if the eventual use is redundant (i.e. health for most of them at the moment), at least they're not wasted potential.
Bread's in the game, and pigs are easier to kill than wheat to harvest and their meat is much better in health supply. :oP
is it really that big of a deal? its not like the update is forcing everyone to go fishing and make fishing there only source of health. besides, lots of people like fishing in games. you might think its just a boring addition but a some people might have really been looking forward to this. :\
God how come it is for ever new idea there are 5 topics explaining how it is bad in some ridiculous way? If you really that worried make a backup of the current build and play offline. Notch knows what he's doing. I guarantee if he made an update that was game ruining he would take it out.