The short answer is, no. You do not have to finish your hardwood floor. Most hardwood floors are stained some color that enriches and deepens the natural color of the wood. They’re then finished with a polyurethane or a varnish on the surface. Alternately, they might be finished with a penetrating oil that seeps into the wood. You don’t have to do that, though. It’s not as common as it used to be, but you can leave the floor unfinished. These are often called raw floors or bare floors. Stains and finishes keep out dirt and moisture, though. Why would you leave your floor bare?
The main reason people leave their floors bare is so that they will absorb dirt and moisture. It might seem counterintuitive since you’ll have to clean your bare floors regularly. However, there’s no way to eliminate all dirt, oil, and dust. Oil and moisture from your skin and from your pets will seep into the wood. Dirt tracked in on your shoes will get ground into the pores of the wood. Spilled drinks will stain the floor if they’re not cleaned up immediately. All of these things are prevented by finishing the floor. However, they’re also the exact same things that give antique floors their desirable patina.
Rustic, distressed wood and reclaimed wood typically have watermarks, oil stains, runs in the finish, and other imperfections. If you want these for your hardwood floor, the easiest and most authentic option is to let them happen naturally. Oftentimes, these imperfections happen to reclaimed wood because the wood was not finished when it was installed long ago.
After several years, you might notice that your floor has taken on a lot of character from being unfinished for so long. Fortunately, there’s no reason you can’t finish your floor later. You can seal in all of that natural aging and patina. You can even enhance it with certain types of stain that will deepen and enrich the colors of the wood.
The main concerns with bare wood are being safe and keeping it clean. If you sand your floors smooth with a very fine grit sandpaper, there’s no reason it will give you any splinters. You’ll clean the raw wood floor with dry methods. Sweep and vacuum it. You can even use a mineral oil or a wax to clean it, but you should know that will act like a temporary finish for your floor.