People don’t like to see their heroes deconstructed, and a jaded Luke isn’t what people wanted from his return.
These aren’t only beloved characters, they’re iconic, tied to the history of cinema and marinated in nostalgia for decades.
New characters stand on their own merits and won’t be judged against some impossible standard.
The Last Jedi was extremely divisive among the Star Wars fanbase, partially because it brushed aside or delivered unsatisfying answers to questions raised in The Force Awakens, but also because of how it presented Luke Skywalker.