Who claims Hogan demanded the title?
Could'nt it be that Hogan gave it as suggestion to Vince that he win should win the title from Yoko?
And if Vince fell for the idea, so be it. Hogan got himself a fatter paycheck so waht, he was marketable and still drew.
Based on what I have come across on that story, Hogan was wooed back in by Mcmahon as once he left, the company saw a real decline and when he returned he bargained for booking control. In Wrestlemania 9, he was relegated to win tag team titles with Beefcake which did not go along well with him for after all he was a star and a big draw who has been brought back to bring up the revenue and not making him the champion in his comeback was unimaginable to Hogan. Hence the angle was added where he ran in and won the title while the tag match had him disqualified.
Post that, there are two stories. One, Hogan did not want to lose and hand over the belt(again, after Warrior) to Bret Hart considering his size and drawing power and hence chose to lose it to the biggest heel at that time whoever it was from whom Bret can win it. Two, Vince told Bret the above story which Hogan denied to Hart and when these three got together Vince was forced to take back his words about Hogan not willing; according to Bret Hart.
As to why they wanted the belt off Hogan, Hogan was not nodding for any of the storylines proposed, not willing to lose clean, not willing to put people over (namely Hart) and did not appear till KOTR once he realized that Vince wanted Hogan to pass the torch again and not as the perennial maineventer he once was; which Hogan was not ready for as he had already done that with Warrior.
All of the above, are merely stories that I have read from various sources, the absolute truth, Vince/Hogan/Bret alone will know.