measure to prevent a possible rejection at the interview. Since you have had an interview and was not rejected by the DAO, waiver is not necessarily needed at this stage. Thus, your lawyer may be right.
I can't recall whether ur case falls under the exceptions of inadmissibility or not, if so, assuming ur lawyer did provide the DAO written material to feed her that you are eligible for the GC, then u should not worry much.
Alternatively, if you had a waiver in place, the benefit is that even if DAO wanted to reject your case, she could not as she had to wait for the result of the waiver. DAOs do not always ask you to get a waiver as a lot of them are not experienced enough to know.
Hope this helps.
I won't have time to visit this site for a while, if any more q, please email after March 7. Good luck