There's a lot of truth in what Soul Stream says. There are so many guitar players out there. If you can play bass, in mean really play bass, you will be a fairly rare commodity. Being a guitar player, I recognized this long ago, so I've tried to develop a bassline/comping approach that will make me more flexible as a player.
P.S. Don't forget to check out classic R&B and Soul records for the amazing basslines that anchor these great recordings.