When learning an instrument, it can seem like a metronome is your worst enemy. It makes playing everything seem much more difficult! It may seem difficult now, but practicing with a metronome trains you physically and mentally to keep consistent time in your playing.
Being able to keep a steady time is essential to playing well with others. When two or more people have the same sense of time, the music seems to lock itself into place and can be very enjoyable to listen to and even more enjoyable to play. There really is nothing like being able to play with other musicians and have the music sound tight, like one cohesive entity.
Playing in time allows listeners and other musicians to connect with the music you are playing. When it comes to music, timing is everything!