Exactly. They actually introduced Serena with a much stronger backstory than anyone else, but failed miserably to develop her motivations/story after the first 2-3 weeks.
It's simple to introduce a new character: they have to make a friend, make a joke, and make a plot point happen. If Serena had befriended Nicole instead of immediately hating on her, while working to get some sort of DiMera disease cured or something, she could have been a great character. And then they could have had the Fred/diamonds storyline after an initial plot that helped someone else out (cured John's coma, revived EJ, whatever).
It's also a good rule of thumb on soaps to connect characters to two leads. They did a great job connecting her to Eric. Making friends with Nicole (or Paige, as newbies at the hospital, or Anne, or ANYBODY) would have accomplished that.
Same fail with Jordan (more EPIC in its proportions though). They isolated her for her first 200 episodes in a giant room with Rafe, or had her sparring with Kate. Snore.
I hope they have bruises on their backsides from landing on the street when they were booted out the door. LOL