I don't think it's about impressing anyone so much. For me I think the Z4C is a timeless design and removing a date-stamped plate makes the car look a little more mysterious, maybe. Obviously anyone on this board could clock it and guess it's from 2007 give or take a year or so, and the first thing I'd tell anyone if they commented is "ah, it's older and worth a lot less than you might think". I'm not remotely bothered about making people think I've a younger car than I've got, but I do quite like its age being an unknown to most.
I'm not sure I'd feel the same if I'd bought a slightly less modern classic from the 70s or 80s.
I do maintain that my car does look better with the LJ56 VZG plates in the bin.