Every pop band and every pop song won't be classics, now will they? If an artist has one song that stands the test of time, he's lucky; if he has many then he's probably not only lucky, but also prolific and talented, as well. We hopefully learn, change, and grow with time, with age; hopefully our favorite artists grow with us - it can be sad to see some 'artists' touring the casinos performing the five hits they had in the 70s, with nothing really new to offer other than repackaged riffs and less clever (or too clever) lyrics.
I still get an urge to give Kansas a listen once in a very blue moon (it has been a couple years or so), but Steely Dan/Donald Fagen/New York Rock & Soul Revue have, for me, kept their appeal since their 1972 debut album, "Can't Buy a Thrill." As an aside, it is interesting to me to have read that Gary Katz of ABC Records, who had hired Fagen and Becker as staff songwriters (Barbra Streisand recorded one of their songs) urged them to form their own band when he realized that their compositions were simply too complex for most rock bands to interpret well. My point here being that some real musical chops may not guarantee longevity, but surely can increase the odds for such.
I love jazz. Classical. Pop/rock. Country. Couldn't well tolerate a one-dimensional diet - know most of you are the same in that regard. When something starts to feel stale, I tend to change gears. After many years of listening, it doesn't really matter so much that the genius of Tchaikovsky lead to the creation of the 1812 Overture, when you've grown somewhat tired of that bombastic warhorse, does it? You'd rather delve deeper and hear his symphonies, concertos, and suites. We can grow tired even of some of the best music in history, even when it's concentrated upon a few, brief years of the personal history of the pop music of our youth.