And how often do you really need to select Rock from 1971 only?

If it were my player, a simple "1971" in the first Year screen would do, since the only tunes from that year on my player are in the Rock genre. In fact, narrowing the genre to "Rock" would actually omit a few tunes I'd prefer to have play in that case. Such as tunes with bad genre tags, or ones that are tagged as a variant of "Rock" such as "Progressive Rock" or "Instrumental Rock".

Keep in mind that complicated cross-section criteria ("All songs from 1982-1986 by bands from Canada with redhead female singers with tattos") is best done by creating custom playlists ahead of time. That's the sort of complex selection criteria best left to a keyboard and mouse, not fumbling with a low-rez interface while you're driving.

The whole poing of heirarchical playlists is so that you can do this sort of thing without complicating the run-time user interface.