Peggye:
I think you're right in that there is a different cultural approach. Also, you can look at the major team sports and understand MLB can promote its past (and obviously there are advantages of promoting the pre-steroid days) and in effect it is still promoting its present so when they bring Mays, McCovey, Yogi, Brooks Robinson, etc. to Yankee Stadium the other night they're putting the spotlight on the sport as a whole and it's a reminder of how rich the tradition is, how great the game was and how great it can be again. Whereas tennis' governing bodies are not always on the same page and do not always share the same interest so it's not as easy to centralize such an effort.
You make a very valid point though: the oral culture and history is vital particularly given what you point about the early pro days that those barnstorming players were sometimes struggling playing from city to city and pro tennis at that time was really a renegade sport so tennis as a whole was divided in those days and you could argue the best players of that time were even willfully diminished by those amateur governing bodies. It would be hard to imagine in today's game Federer, Nadal, Djokovic traveling by car to play in places like Wichita or Wisconsin and not being able to contest majors. You can argue that tennis - or at least some authorities in tennis - have had a history of cannibalizing itself at times. And while there have been some tremendous tennis books: Handful of Summers, Levels of the Game, Ashe's books, etc. - they aren't nearly as popular and don't occupy the same shelf space (recently tried to buy a few copies of Handful of Summers here in the city and have yet to find it).
Also, in many ways tennis is more inaccessible to the average sports fan in that almost every kid in this country who has attended school - boy or girl - has swung a bat at a baseball or softball, shot a basketball at a hoop or kicked a ball at a goal, but you can't say that all of those kids have swung a tennis racquet. So I think those subtleties that we - as tennis fans and rec players - can understand and appreciate can get lost in the translation to someone who hasn't had that experience. That's not to say someone who has never played tennis can't be a great fan and appreciate the sport just as someone who has never run a marathon can appreciate just what a feat it is watching someone complete one, I just think that is one of the reasons why it doesn't cross over as much. Richard Evans just wrote a fascinating piece comparing the Nadal-Federer final to cricket in asserting that the longer best-of-five set format in Grand Slam tennis allows drama to build over time in the same way that test cricket played over 3 to 5 days does what the new form of cricket "TwentyTwenty" cricket does not (will post his piece once our server is back in working order).
I also think that the advantage team sports has is the loyalty and affinity to a franchise. A Yankee fan who grew up rooting for Jeter may have never seen Mickey Mantle or Bobby Murcer play, but on some level understands and recognizes their role and importance in their team's history whereas tennis fans tend to have a favorite player and may not see a connection from Tilden to Don Budge to Kramer to Gonzalez to Agassi, but I would argue there is a connection there - just may not be as obvious.