I heard it was because of the T for Teen rating and that in Sims 1 people complained about the "inappropriateness". Have no clue if this is true, I saw someone mention it on the EA forum a while back. I think the closest we'l get to drunk sims is the way they act when making nectar. I rather like the moodlets you get from the LN bar drinks.. I think that's enough, for me.
I don't think thats why, on sims medieval you can be drunk, it's rated T for teen too. Oh well, EA can be a little, strange. Oh, and I wish they had more of a variety for animals on pets. Like rabbits, frogs, squirrels, oh, and if they ever put a sim town with an icy climate, I would want penguins. And I also wish you could go to a walmart on the sims 3. You know, buy the cloths, and buy different kinds of tropical and freshwater fish for the fishbowl instead of having to catch the fish.