Many religions other than Judaism have a restriction against eating pork and other things.
The big three things in being kosher is no pork and shellfish, as well as avoiding the mixing of milk and meat.
I don't kept a kosher kitchen with separate sets of dishes for milk and meat, different frig, dishwasher, to avoid the different dishes touching. Nor do we ever buy (expensive) kosher meat.
Kosher seem hard but it is as hard as you make it.
People are vegan, gluten free, and lactose intolerant, which are all way harder than not eating pork or shellfish.
Why do it?
G-d can see all futures and if he knew at another time in life we would be able to make the kosher laws not valid he would have said so. He knew the world was round and it is said "He who sits above the circle of earth." This was write hundreds of years before anyone found out the earth was round. So he knew how things would change. Maybe at that time it was due to not having clean ways to eat pigs or shrimp. But for us it is about the fact that he said so. He said not to do it. If someone came to America today and said it is fine to eat Monkeys and they were starting a farm to raise monkeys to be eaten would that mean we will all start eating monkeys. No I think people would still feel that eating Monkeys wasn't right and some would not do it. But the next few generations would grow up with Monkey restaurants and they would start to eat monkeys with no problems. Well that is how it is to be a Jew. One person said it was ok to eat these things and even if it is out dated and made clean now it doesn't matter because we know we are not suppose to eat it for no other reason than because we were told not to. It is just like being a parent. You don't have to tell you kids why they can't do something that they think is fine to do. You know what it is best for them even if they think you are wrong. G-d is our father and he knows what is best without us undermining him with why. So no it is not out dated. This falls under the rules of "because I said so and I am the parent."
If you want more information on being Kosher and all the rules