Except people who say that TLJ provides a radical new interpretation of Luke are wrong. Luke has plenty moments of skepticism in the OT. He’s also 35 years older than when we last saw him, and he’s seen a lot. It’s reasonable that a character could develop during that time.
In fact, if Luke were precisely as we left him in ROTJ, that would be less believable.
Also, given the plot of TFA, how did people not see this coming? Why is it suddenly shocking with TLJ that Luke isn’t a gun-ho optimist let’s fight the FO! Infinite Jedi!