Agreed, Crusher is a rather bland character who writers always seemed to struggle to write for. It got to the point on TNG where they actually began rewriting episodes originally intended for another character as Crusher episodes because otherwise she wouldn't have had her own episode that season, like Suspicions which had originally been written as a Geordi episode. Hell, even the old post-Nemesis novel continuity where her and Picard were married and raising a child together only gave her minimal roles, to the point of actually introducing another medical officer as the Go-To for medical matters in a book's storyline.Thing is, I never had all that high of regard for the character. She was just very bland, 90% of the time. McFadden was capable, she could hit it out of the park, with the right material. "Remember Me", "Sub Rosa".
So while there is truth to the claim that Picard S3 turned her into a horrible person, by doing so it at least actually did something interesting with the character for the first time ever.