I'm going to go against the norm. Many folks on BYC like to spoil their birds. It is nice to give them more space? Yes, of course. Will they be fine without it? Yes, they will be fine in the space you have. For starters, they don't know any different. Do chickens get bored? Who knows. Boredom is a human trait we like to pin on our animals, but whether or not they ever actually get bored is unknown. My chickens have been in a fenced run their whole lives. Sometimes I wonder if they are missing out on the excitement of the big world on the other side of the fence, but then on occasion one will get out, I will leave the gate cracked while I tend to the food/water, and a chicken will wander out the gate, you know what they always do? They panic trying to figure out how to get back INSIDE their run. Providing consistency and providing a run provides them with a sense of safety I believe. Do what you are comfortable with. You can always expand the run later or give them a secondary fenced area. Good luck with your new chickens when they arrive! I hope you love every minute of it!