"All comparisons are odious".   Oh, joy. There's no such thing as quality in music, and we must not judge that one is better than another. No difference between Chopin and Manilow. And Mozart and Neil Diamond, I suppose.

Sorry, SRS, you can regale us til the cows come home, if you choose to, with the wonderful finery the emperor is wearing.   But he's still naked.

There is a difference, and a comparison can be made between the Chopin which has at least some musical merit, and the Manilow which, shall we say, has less--and no connection to the Chopin musically except in a young listener's vivid imagination.   I trust you're not as young now.

And it's not just my prejudice against Manilow. I even actually like one of his hits--Copacabana. I've been a big fan of pop opera for quite a while--as long as it's over in about 3 minutes. "Leader of the Pack" and "Dead Man's Curve" are two well done pop operas. Copacabana fits solidly in that tradition and works well. It probably helped that Manilow did not write it by himself.

If your expectations are low musically, you can appreciate a lot of pop--but I'm under no illusion that any of Manilow can hold its own musically with Chopin, even a modest Chopin like the one cited.   Nor can it hold its own with most other pop, Copacabana being the only exception.

Your candidate to illustrate how a classical piece "became" a pop piece in the hands of pop singer is just not the best choice. The irony of course is that your general point is completely valid. If you had said that a part of the Anna Magdalena Bach Notebook "became" "Lover's Concerto", as sung by the "Toys", your position would be much stronger. However, citing "Magic" as a pop realization of Chopin is way off target.