I sometimes do, because some of the records I own were never released on CD or are hopelessly obscure, and also because I don't own them on CD or can't find a good-quality MP3 to illegally download, which I'm not supposed to be doing anyway.

But yeah, I guess for stuff like The Beatles and Michael Jackson, this wouldn't be necessary. The advantage of having the dynamic range and non-compressed mastering of a record usually doesn't translate that well into self-made MP3s with these things, in my experience...although my USB record player is not the greatest.

Also, unless you are willing to pay over $600 you shouldn't be using newer players anyway unless you are DJing, in which case you will find it's not feasible to use your vintage equipment anyway. In my opinion, that is.