About a week ago we got a 8weeks old black lab puppy, having done a lot of homework, we decided to crate train him, he does like his crate, we feed and water him inside, however he doesn't seem to like being closed up inside, its not to do with being on his own, because he goes to bed at night in the kitchen with the crate open, and he's fine. My question is, even though right now he's very well behaved, is it the wrong thing to do to allow him to sleep in the kitchen without locking the crate, as what is the real purpose and as he gets bigger and chewing becomes more of a problem, we won't be able to close him up. Should we just continue to allow him to sleep with the door open, if that's what makes him happy?

It really depends on where you plan of keeping the lab when he is older.

If he is allowed to have the crate door opened when you go out or are sleeping then it really is up to you, it will have no ill effect on the dog, it is the same as someone having a basket for their dog to sleep in instead of a crate.

But if you plan on locking him in the crate when you go out or at night then you must not leave it open for him at night.
Leaving it open sometimes and not others will only confuse him an the times where he is locked away he won't understand and think he is being punished.
If you start always locking the crate at night or when you go out now, every time then he won't think it is a punishment, he will just take it as "this is what happens when they go out"
Always remember to leave fresh water in the crate and plenty of toys to stop boredom.
You could even consider leaving a radio on for him when you are out as this often stops them from crying or barking.