Dutch are such pretty rabbits; congratulations to your family and to the bunny!
Spaying/neutering is one of those much debated topics when it comes to rabbits. Anesthesia is difficult in rabbits, and doing surgery on an animal that may only weigh 2 pounds as an adult isn't easy, either, so getting a rabbit spayed is usually an expensive proposition. Locally, the cost of the surgery is about 5 times the price of a rabbit, so you can see why there aren't a lot of folks that opt for it around here!
There is a certain amount of undesirable behavior that may crop up in unaltered animals, but whether that is hormones or just that rabbit's personality is hard to say - some of the friendliest rabbits I have owned were intact females. Most bucks and some does spray to mark their territory, but that may or may not be stopped by surgical alteration.
Probably the best argument for spaying has to do with cancer. There is a high incidence of cancer in the reproductive organs in rabbit does - but just how high, I'm not sure. I have heard it said that something on the order of 80% of rabbit does will develop cancer by the time they are 3 years old. This is said to be the reason that does' fertility usually starts dropping by age 3, and the reason that most does are effectively sterile by the time they are 4 years old (if they are still alive at that point). Some say that the high rate of cancer occurs in breeding does, others say it is non-breeding does, some say it may be breed-specific; I don't know. All I can say is that I have had a lot of bucks that lived to be 8, 10, even 12 years old, but to have a doe live more than 5 or 6 years has been rare in my rabbitry - and that seems to be regardless of her breeding history. So in theory, getting a doe spayed may double her life expectancy.
Yes, I've heard the cost for spaying at some vets is up to $200 - $300, so I feel like we got a pretty good deal getting her and the surgery for $70. That said, the principle still kinda bothers me that I didn't have the choice. I mean, I understand with cats / dogs to get them fixed since there are so many around that it's almost inevitable they will get pregnant, but a lone bunny that's always inside? The probability of our bunny ever being anywhere near another bunny is really low, if not zero.
Well, what I do know is our girls are so totally in love with this bunny it's amazing!