Space and privacy, staying at the hotel most likely give you a small room with a bed or two and a desk to be likely. Most of the people tend to stay outside of their rooms during the stay but at a bed and breakfast, you get more chance of experiencing other things and enjoying your stay.
Breakfast is included, coming from the name itself you can just be on your bed and enjoy your delicious breakfast.
Explore more areas, one advantage of staying on a bed and breakfast is you can explore more areas rather than staying in busy places for the time of your travel.
Meet other travelers, staying on a bed and breakfast gives you a chance to meet other travelers which can be your friend. Staying at a bed and breakfast usually makes you meet a lot of people making it impossible for you to not make friends.