Think of meds as something to take for symptoms, maybe. With BPD we have intense anxiety and/or depression and there are meds for that. For the causes, there is therapy.
To me, BPD is like a stunted development. We do reach adulthood, but we haven't developed fully. We have immature spots in our development that affect our perceptions which in turn affect how we deal with things like being alone, being in a relationship, speaking up for ourselves, so many things. We can feel hopelessness and anger intensely and easily and that can lead to depression and anxiety.

I can only tell you my history about meds. I feel it is up to the patient to take or not take meds; others feel differently and it might depend on the level of functioning the patient has at the time meds are considered.
I took meds for depression for many years. I decided to see what I was like without them because I felt emotionally numb. I wondered what I was like underneath the meds after all these years, so I went off them. I quit smoking and anxiety became unmanagable. I found my way back to therapy (this time researching and finding what kind of therapy and therapist I wanted) and shortly after beginning I read "let me out of here" by rachel riland, her experience with BPD. I thought the diagnosis fit and asked my therapist; she had already decided that BPD fit me although she hadn't yet shared that with me (she doesn't want patients to get too hung up on diagnosis). By sheer coincidence I had chosen a therapist who not only was psychoanalytic, but also specializes in BPD. Lucky me She introduced me to the idea of attachment disorder and that BPD is a disorder of early development. We discussed meds and she is neither for nor against, and stated that they are often helpful during difficult periods of therapy.

Anyway, as far as meds go, if they are suggested and are helping, then that's good.
If you are not sure about the role of meds in your treatment, I really encourage you to talk to those who provide your care.