Long question first:
I was watching a bit of SummerSlam ’90 a while back and after the Hogan/Quake match, I thought about how Earthquake gave Hogan almost nothing during the match. Now, I realize that Hogan’s matches against the big monsters were often built along this philosophy to maximize sympathy for Hulk, but it still struck me as a bit strange given the whole "Hogan seeking revenge" aspect to the build-up. I momentarily wondered if they were saving something for the subsequent house show run, but then I remembered an MSG match that I saw ages ago that wasn’t much different in terms of the ratio of Hogan offense to Quake offense.
Obviously, the feud drew a good buyrate for the PPV and further strong business for months around the horn, so it probably wouldn’t have been wise to tinker with the formula too much, but still would it have been too out of line to restructure the matches a little so that Hogan gets a few more licks in at the start to satisfy the "revenge" narrative (namely, a bit more like Hogan against Bundy at WM2) before going into the extended heat segment? Or should we just say "don’t argue with success"?
Second (shorter) question: was there anything to the story about Vince wanting to get Nikita Koloff to headline WM2 against Hogan, but Nikita didn’t want to come in just to job to Hulk? Was this actually in the works at any point, or is this just a wishful "might have been" story passed around by fans?
The Quake thing definitely seems to be "don’t argue with success". Hogan obviously knew what he was doing, and yeah, if he destroyed Quake at the PPV then there would little left for the house shows, which also did big business for them. Maybe he was even saving something for the NEXT run of shows, because Hogan-Quake matches I’ve seen from December-ish are pretty much Hogan wiping out Quake by that point.
As for the second one, there’s no definitive evidence that the Nikita jump was a viable thing. I’ve heard many times that Vince WANTED it to happen, but I don’t think a concrete offer was ever made. The timeline just wouldn’t work out. It would certainly have been an awesome WM2 main event, however.