I disagree that royal weddings aren't popular.
Regarding Eugenie's wedding, her wedding was broadcast live in Great Britain, Australia, the U.S., and probably other places. IIRC it was also re-broadcast in the U.S. The British and Australian outlets that covered the wedding got much higher ratings than they usually got for the timeslot. A crowd showed up at the church and people lined the streets in the town of Windsor along the route of the carriage ride.
It was even broadcast live in Italy, just saying. And ITV had the highest audience for that time slot since the Cambridge’s wedding. For a privately-owned TV I find It hard to think ITV refused not because of Andrew.