Oh no, I'm not kidding. I dislike season 8 and the first part of season 7 but I HATE the second part of season 7. That extremely boring and embarassing moment has nothing to do with the show that I'm found of!
Sure, Linda Evans and John Forysthe did a great job, just like Gordon Thompson did with the unbelievable story "I'm may not be Carrington after all" or Jack Coleman and Heather Locklear with their "no love affair" but what a nice acting uses for when the writing is so desesperately poor and insipid?
Who cares of that little girl who was still a baby three episodes before? Who could really believe that she could die? Who didn't forecast everything Sarah Curtis did for 7 episodes? What a miracle Sarah lost her daughter exactly the day she met Dex Dexter after several years without seing him! What a miracle Krystle and Blake are enough stupid to let Sarah taking care of their daughter...
On E!, they show a part of an article published at the end of that season (even though it is wrongly showed when they talk about season 9...):

"Joan's drone, Blake's bleak and that whiny Krystle... quick, find me a pistol. ABC's Dynasty, once a camp marvel, is now a travesty. The Carrington mansion (...) has became a mausoleum for middle-aged (...) Alexis trades her champagne-and-caviar charisma for a milshake and hot-dog at a roadside stand? Uh-uh..."
It's not that the rest of the show is particularly well written (excepted seasons 1 and 2) but at least there is some distance between what's going on and the tone of the narration. There's an awareness of not being too much serious (especially in the first part of season 6, that may be unintentional for the rest of the show) which is underlined by the permanent irony of situations and dialogues. No cancer, no children killed, the "hardships" that the Carrington experienced provoked tears and laugh at the same time. The show plays on both the specific identification of tragedy and the need to put distance in order to enjoy the implausibilities and excesses without blushing. At least, that's my vision of "Dynasty".
Like season 1 and most of season 2, the second part of season 7 is supposed to be extremely serious. OK. But the two first seasons are excellently written whereas those 13 episodes are not. Every moment is supposed to be dramatic but fails to be moving. I guess that's why the writers return to campiness in season 8, being unable to write a good piece of work like in the good old days. Unfortunately for us, in 1978-1988 they turned to be also unable to write that "camp marvel" and the "travesty" continues. But at least, it was less boring to watch...