More seriously - banks are convenient, especially for money that you're regularly doing stuff with. Vs. if you have $College_Tuition_for_Kid, and know you won't touch it for (say) 6 years - then buying a 6-years-to-maturity bond can make good sense.
But neither bonds not the bond market are simple, learning about and dealing with them takes time, and if things happen that your smart strategy wasn't actually prepared for...