People are still clinging to that are they
When Harry got engaged people were 'oh they don't need to film it no one will want to watch. He is not the heir. there is no interest. He is not the heir.'
People don't watch due to how close you are to the throne. A good majority of people who watch royal weddings now a days see royals like celebrities. They watch those who are exciting to watch. The playboy party prince marrying the bi-racial divorced American actress. No one cared if they were not next in line for the throne. Harry being Diana's son, as well as his own reputation and his wife, made them tune in.
People tuned in for Eugenie to see the royals attending. To see all the celebrity guests in attendance. And because her parents are scandal ridden.
Edward and Sophie were older, and boring. There was nothing exciting about the couple. The attention had long moved from Charles' siblings to his sons when Edward had married. And even then there was some interest in his wedding as there always will be.
Beatrice is the last royal wedding until George gets married, or a sibling if they get married first. Her father is scandal ridden. There is no reason to think she wont draw in some attention.
Even if the 'royal fans' who only care about the degree to the throne a person is don't tune in, there were are plenty who would for the spectacle.