Here's the simple truth :
Games have been MSRP $59.99US for a while now.
Gen5 native games : $49.99-59.99US
Gen6 native games : $49.99US
Gen7 native games : $59.99US
Gen8 native games : $59.99US
Now for this gen, Sony and third parties upped the price to $69.99US.
Sure, 10$ uptake seems quite the jump. They probably should've made Gen8 native games $64.99, but no one wanted to risk it back then.
Ironically, it was Sony with it's disk drive based games that drove the prices down compared to Nintendo cartridge based games.
The fact of the manner is, videogame prices haven’t kept pace with the value of a dollar. (Source: U.S. Bureau of Labor Statistics data)
Basically, the price of any entertainment went up in the past 15 years, except videogames (ie : The price of a movie ticket, etc).
Publishers came up with ways to extract more dollars by offering "Deluxe editions", DLCs, microtransactions, etc.
The GoT situation is the logical conclusion from that : PS5 native GoT is $10 more then it's PS4 equivalent.
And you can be damn sure that once Microsoft releases a Xbox series exclusive native game, they're going to price it MSRP $69.99US.
But like many have already said in this thread : vote with your wallet. If you don't think the PS5 enhancements are worth 10$, stick with the PS4 version, which already received a free 60fps PS5 patch, plus a whole new multiplayer mode.