It’s so bizarre to read this in the present, knowing how incredible TNG was, but I get it - the original crew WAS Star Trek to them.
The dedicated fans revived this series in syndication, well after it had gone off the air in 1969, and felt attached to the characters that they had obsessed over between then and the 1980s. Like modern fans, they thought that departure from what they knew would ruin it.
I wish I could go back in time and tell them that TNG is going to rock.
I came here to post this. I remember someone insisting it was like casting Gary Coleman as Two-Face.
Although the response wasn’t as strong, there were fans who were also convinced that Robert Downey Jr. was a poor fit for Tony Stark.