I think it's pretty common - most people in my MA program had applied to phd programs and gotten rejected. That being said, I know plenty of people who got into phd programs with just a BA. I think I was unsuccessful because my research interests had changed and I didn't have such a relevant writing sample. My MA year allowed me to work really hard on a writing sample (my thesis), prove I could succeed in graduate coursework, and get new letters of rec. Our advisors told us why we weren't accepted to the phd program, and for many people it was the writing sample, not having enough research experience in the field, lack of theory courses, or undergrad from a less prestigious school where the letters of rec and grades mean less to the admission committee. I definitely think it's smart to try to get into a phd with only a ba, but if you don't get into a program you're excited about, doing well in an MA program can help you get into a top phd program with funding.