they put better mixes on records for pure marketing reasons.
Not quite, although overall I agree with your assessment of the situation. Among other things, vinyl actually requires what I would call a "dumbed down" mix/master-- that is, it can't be too loud; and, in the low end, there can't be too much stereo information. All of these are related to the physical limitation of the needle and the grooves necessary to reproduce sound on vinyl.
That said, depending on the genre you like, you might like vinyl *mixes* (which *are* in many cases different mixes than ones you might hear today that are "remastered for iTunes"). This is because songs on vinyl are mixed and mastered more dynamically (or, "quietly"). Modern digital music tends to be really really loud, so the difference between loud and soft parts is kind of negligible. Certain genres, of course, lend themselves to loud-- EDM, heavy metal...
I really don't care about vinyl either way, except that I think people who think it is a better medium for music are complete suckers. The science behind "vinyl is better" is one to be understood in terms of packaging and tactile experience, and has zero to do with audio in terms of the vinyl medium's ability to reproduce sound vs. digital.