During the time when we couldn't find a bass player, we actually did a couple of live gigs anyway, and decided that we didn't want to play in public again without a bass. The lack of low end really takes the power away from your sound. But there are many advantages to playing bass. First off, in my opinion, the instrument is easier to learn and play than guitar. You won't have to worry about making awkward chords, or breaking alot of strings.
Many bass lines are very simple, and yet they add so much to a song.
However, if you really want to become a skilled musician, you still have the ability to learn techniques that will impress people. A bass player with a good slap technique is always appreciated. You will learn just as much about scales and music theory playing bass as you would guitar. And you have your choice of playing many different types of bass. Learn to tame the Chapman stick, or play an upright.