So Harry and family are coming back!

At least Andrew has just quietly shut up and retreated to a private life. No arguments or PR 'leaks' like his nephew.

"If you think about it, it probably mirrors much of the narrative about Edward V111 and Wallis Simpson. How very dare they walk away from the institution."

Not at all.
Had they just walked away and lived their lives with dignity instead of very publicly tearing their families to shreds time and again, most people would have had a great deal of sympathy with them and more or less forgotten about them.
The media has not sought them as much as they have sought limelight in the media. They do not want to be forgotten.

Their situation is quite different too, in that Harry was the Spare (which should be a relief, not the cause of resentment it appears to be). His place in line has moved down too.
The Duke of Windsor was a Monarch, the Head of State, and abdicated that position.

"I don't look at Harry and Charles as members of the institution, I look at them as father and son."

Just to add that we don't know what their private relationship is like now, but, as Monarch, who has certain members of his family also carrying out duties on his behalf, Charles and those who support him in his role had to make it plain that Harry and Meghan are not returning as working members of the Royal Family.

This just makes the public aware of the line between the family and the Firm.