Most of the stations - esp in S Brooklyn, outer Queens and The Bronx, serve mainly commuters and New Yorkers ( I mean seriously, how many tourists go up to see the hall of famous americans in The Bronx ? or the Bronx Zoo ? or the Brooklyn Museum ? (fabulous Egyptian collection btw)
Tourists need mainly manhattan, and the existing map does ok; the main problem is the multiplicity of trains on the tracks - local and express
If you are a serious tourist, get a Guide Michelin, or whatever the e-quivalent is; it will tell you what to do to get to the Brooklyn Museum, or the Morris Jumel Mansion, or Lydig ave, or...
Anyway, I assume that like me, many of you have been in London/Paris etc, and I seem to recall from my long ago student days that relying on the subway map often led to long, unexpected walks.