Having a good technique is immensely important. You are going to find that certain styles of guitar require that you have a good technique in order to be able to play them.
Often when you are studying sheet music or playing along to songs by ear it is easy to overlook technical exercises and one of the reasons that you may struggle to learn things is because you need to improve your technique.
Good time spent practicing exercise allows you to really concentrate on what you are doing with your hands. Improving how you hold the guitar, use your pick/fingers and generally being more efficient with both hands will vastly mprove your dexterity and the speed with which you play and learn new material.