You can learn flying a trainer ignoring the rudder. The rudder will give you smooth turns, but it is not truly necessary to simple flights. When i learned flying with my trainer i rarely used the rudder. Now i can't live without it. It will give you more control of the plane, you will be able to do smooth turns, and help you in crosswind landings. If you get a sport/3d plane, then you will have loads of uses to the rudder, cause a lot of maneuvers uses the rudder. Ohh... and you will never be able to make a knife edge without the rudder