The most common reason would be because your old flooring has become discolored, dull, has marks you cant remove, or has chips in it. Stripping the floors may be the quick way to make your floors look brand new again.
Some great reasons for stripping a floor include the desire to change the stain color, the need for refinishing due to nicks and scratches and to remove buildup from waxy floor cleaners.
One reason would be for preparation of redoing your floors. If you have cuts, nicks or gouges in your floor you want to strip then and fix them. Perhaps you want to change the color of the finsh.
Stripping a floor is usually done if the current finish on the floor is ruined or there are many coats of finish on it. Stripping it gets rid of all of the old coats of finish for a fresh look.
You may want to strip a floor in preparation for refinishing hardwood floors. You can also strip floors to put another flooring on top like tiles, to ensure a good seal.
One reason you may want to strip a floor is if you have an older or antique wood floor that you don't want to sand. Stripping it allows you to preserve the character and originality of the floor.