Doesn't bother me in the least. So far slaughterfish have been rare and do very little damage. Fighting underwater doesn't really make sense anyway unless you're going to add some game play to it.
Exactly. I'm sure there are lots of modders who planned to do something about it and add gameplay if Bethesda didn't - note the mod I mentioned "Alive Waters" for Oblivion. But without the basic mechanics of combat underwater, I'm not sure I understand how the modders will be able to add that gameplay content. That is frustrating, since I have greatly enjoyed the enhanced & vibrant water mods that have been playable for past games in the series. This was a real surprise for me. And seriously - what is the point of water breathing now?? And why aren't at least some weapons usable underwater... has been mentioned... spears, daggers, and crossbows (aka spear guns), etc? Meh.
Actually, I consider water-breathing useless this game around not because of pithy water fighting; Argonian's don't get much use out of that ability because there isn't much down there. When I had an alteration character with water-breathing I was just itching for Dungeons that were submerged or had long underwater tunnels. Deep dives and dark caves! Or just dead things, crashed ships, and secret underwater cave treasure. I searched high and low for a good application of my water breathing ability, some secret under the waves, and I came up disappointed.
Yes, that is also annoying. But if the basics were there, modders might be able to do something with it. IMO.