When I was young we had several bunnies who were outgoing, active and friendly.
Now I have two Dutch bunnies and they only sit. They have a very large enclosure with straw and hay. They were friendly and outgoing when young but now they are about two years old and seem to have lost their human social skills. They often just sit next to each other.
They are healthy, not aggressive and very tame and easy to handle. When they free range in the house, they sit under a table and just sit. They are not afraid. So what's up with that?
When rabbits get older they get lazier - simple as that. Some have very active personalities and love to explore and will continue to do so into old age, while others pass the 1 or 2 year mark and settle down for extended naps. It sounds like your bunnies are very content to just sit and nap and hang out. Dutch bunnies tend to be known as smart and troublemaking bunnies, but it sounds like yours are just the more quiet and mellow type.
Also, bunnies who have a partner can find it easier to just spend time with their bunny friend and not spend time with people. It can help to really try to bond with them and spend one-on-one time - you can teach some simple tricks, get some treat dispenser balls, or other active toys that will encourage them to interact with you.
Also, bunnies who are free range can be quieter. They don't spend all day waiting to expend their energy outside the cage - instead, they can move around whenever they want, so they're less likely to get out their energy in big displays of binkies and bunny 500s. I'm not suggesting you lock them up more, but it can help explain their behavior, especially in contrast to the bunnies you grew up with if those were caged most of the day.
I love dutch rabbits! mine loves to be cuddled,
but is a naughtly little thing! Always chewing and
redecorating her cage by pulling everything around!
Shes been a happy camper since day 1!
But some buns just like to sit and enjoy the company of bun friends.
my walter is just like that too, he is happy as can be just lounging in his cage, and he is a free range bunny so he doesn't have to be there. he is bonded to my rex rabbit but she is the one who likes to explore the house and check things out. plus there is an age difference, my rex is only 6 months old and walter is over a year (not exactly sure as he was a rescue). we refer to him as "the old man" because he is content to just sit around and observe his surroundings.