It is also very relative. Your perception of what small means, may be totally different than reality. But, let's attempt to perform an objective analysis.
When you buy a small sail boat and pull it into your driveway, you'll quickly notice that it's very small. Don't have visions that you have bought a yacht, or a keelboat, or a cutter. It could be as small as an 11-foot mono hull. A small sail boat, on the other hand, could be a racer or it could be a day-sailer.
Small sail boats do not have cabins but they could have some form of partial shelter. This is important to consider when you do your purchase analysis. As is the consideration of whether they have a portable toilet. But, they're certainly not going to have the amenities of the large sail boats.
The small sail boat is a good first boat to learn how to sail. If you make an error, it lets you know immediately. You can then learn from your mistakes, as you go. You'll become exposed to many important water experiences that you would miss if you started with a large sail boat
One of these experiences is capsizing. Capsizing is certainly not fun. It teaches you about one of the dangers of sailing. It teaches you how to right a boat. It teaches you how to develop and practice a recovery plan.
Sailing clubs teach children, many times, as early as age six, to become proficient on the small sail boats. As they become knowledgeable, they progress on up to larger sail boats. There are many advantages for young boys and girls, as well as adults, to start on the smaller size sail boats. One of these advantages is price.
This is not to say a day-sailor cannot be a family boat. You can take a small sail boat across the bay or along the shore line for that picnic, fishing trip or little jaunt. But, it is not recommended you get too far from shore.
Of course, where the small sail boat shines is in the racing world. Without getting into the specific special high speed designs, just note that these are built for speed, and not for comfort.
Remember, a small sail boat can truly be a beautiful and pleasurable thing for everyone in your family. It can draw you together as a family unit. And, what could be more important!