Sometimes, shows have no choice. If you think about it, Will has been played by several actors, so has Abby. Matt Ashford is the 3rd Jack Deveraux and truly made the character his own. Mike Horton has been played by 14-16 different actors., Shawn & Belle by a few different ones.
While sometimes it is hard to get used to someone else in a role, heck, stage plays do it all the time. We get ingrained with loving the one person in the role (Mary Martin as Peter Pan, Julie Andrews, Sound of Music & Mary Poppins....the list goes on) but we have seen others perform those same shows and very well. Hello Dolly comes to mind, which I saw with Carol Channing, that role was HERS for sure, watched the movie with Barbra Streisand, on PBS with Pearl Bailey....Bette Midler has played her, and currently, on Broadway, it is Bernadette Peters. Plua a myriad of others in various cities, road shows, local small town or high school productions.....
I do agree that Eileen Davidson was Kristen.....but to me, she owned the other characters, Susan, Sister Moira, Tommy.....And she was unavailable, evidently so the show decided to recast.
Am certainly willing to give any actor a chance, so for me....especially since others think highly of Ms. Haiduk, I will wait and see.
Let me add that I really see no need for Kristen at all on the show....but, I don't write it, so.......