I agree with this. This was back in the day when DH was still Roman. Plus, I'd been a Luke and Laura fan yet I found her very appealing as a more grown-up, professional character like Diana as opposed to just Luke's other half. I still have some Roman/Diana stuff on tape. Didn't the return of Deirdre Hall/Marlena basically mean Diana/Roman were doomed?
I would also say Mary Beth Evans as Katherine on GH. Despite her fairly long tenure on the show (around 5 years or so) and MBE's ability to pull off comedy, bitchiness, compassion, etc., the character of Katherine never seemed to be written as the focal point of any story. She was always an appendage to another character...Damian's partner, Lucy's rival, Mac's girlfriend, Stefan's latest obsession. She was just there to be somebody else's foil, or to react to someone else and she didn't have any family connections of her own. I mean, I had loved MBE on Days but there were plenty of times on GH when Katherine was in a scene and I just wondered what she was doing there.
Katherine was something of a mess of a character. I don't think they ever had an early idea for her beyond, "Kayla will be a bitch, that will get us some attention," and the later attempts to tame her were not believable. I thought MBE did a great job, considering.
Genie left a year or so before Deirdre's return. Supposedly she wasn't happy with the role.