There are two main reasons that riding gloves are worn. The first is to protect your hands in case of an accident. The other reason is to provide good grip on the handlebars and prevent accidents like that from happening, especially in deteriorated weather conditions.
If you ride an ATV or Motorcycle, the palms of your gloves will be very important, since when you take a spill natural human reaction is to spread your palms and attempt to break your fall. This will lead to a major case of road rash on your hands if you aren't protecting your hands with a good pair of motorcycle or ATV gloves.
For either type of riding, flexibility is an important concern. You need to be able to grip your handlebars tightly for good steering control and you need to be able to have lever control. Check out the styles of riding gloves available at Raceway and you will notice not only are they made of lightweight materials, many have pre-curved fingers to insure a good grip.
Previous styles of riding gloves had fingers that would bunch and prohibit the rider from getting the best grip possible on the handlebars of their ATV or motorcycle.
Keeping your hands warm is a job most good riding gloves will do for you. Thor makes some great gloves in their line for this purpose that are well within anyone's price range.