And yet, SST has gone through so many changes since the 90s for the exact opposite reason: the original magazine format was because kids at the time liked commercials inbetween shows, but they shifted to the block format in 2002 because kids then prefered repetition and predictability; the street itself was like an innercity street in the ghetto because that was the kind of locale their target audience lived in, but over the years has been cleaned up and brightened up because so many of these urban areas have been gentrified, and modern kids wouldn't recognize the mom-and-pop-type stores of yore like the Fix-It Shop; the show has been shortened from an hour to a half-hour because kids today can't sit still through an entire hour of something (that, I can attest to, if you've ever seen a kids movie in theaters, you'd know all the kids do is run around and scream their heads off in the theater).
But at least you can give props to Mister Rogers for sticking with the same thing for all the years that he did.