I trust my instincts, as well. In my case, major issues didn't begin to arise until the game had progressed for nearly 2 years. Table rules may not be for everyone, but at the very least I've come to believe that being up front with everyone's expectations for the game is helpful. Most of the problems I encountered had to do with some players expecting one thing from the game, and others expecting something else. They both went along, expecting different things for the entire time, because there was no agreed-upon expectations for what was what in how the game would be played.
That's not the kind of thing that's always immediately apparent, but it is the kind of thing that a set of table rules can "head off at the pass." It certainly seems to have helped in my case, as going without only resulted in bruised feelings and lost gamers.
Besides, there aren't necessarily universal social mores, even among gamers. It might be perfectly acceptable to play videogames any time its not your turn in some groups, while in others, that's a deep and abiding annoyance. Even if you, as a player, don't care one way or the other, that's the kind of thing that table rules can lay out for someone who doesn't know.
It's certainly better put it on paper than have the DM (or another player) bitch them out for what they thought was perfectly acceptable.