Every surgeon will perform every operation a bit differently. As more and more operations are done surgeons typically alter their techniques a bit and as more and better techniques become available most surgeons will change their techniques to keep current. No surgeon likes complications.
I am sure your plastic surgeon performs this procedure a certain way because she is comfortable with it and she gets good results with few complications.
If you are not comfortable with her choice I think you should discuss that with her. Your weight has no influence on whether or not a drain is used.
Thank you for your question and good luck.