I think puppies are just like small children. They hate to be sent to their rooms when they are young, but as they mature they begin to appreciate having their own space. My babies all have their own individual crates that they stay in when we are not home with them. After the juvenile period passes, my dogs have always enjoy going into crates on their own just for some alone time. My adults will go into their kennels on command without any incident and sometimes they will just get into them when we are home just to hang out and be left alone.
My one year olds are quite there yet
but I am sure they will get to that point too.