The idea that Merckx or Hinault or whomever, if riding today, would approach the racing season as Lance does seems reasonable on the surface, but it ignores the environmental influences that form individuals.
If Merckx was born on the same day as Lance Armstrong, he would have still been raised in bike racing central, Belgium, and as a child dreaming of being like his idols, he would have wanted to ride classics and win Belgian races, especially Flanders, then P-R, etc.... Plus, the peer group he responded to would have given him lots of pressure to succeed and then positive reinforcement for success in those races, quite possibly as much as lance receives for success in the TDF.
So it would seem more reasonable to believe that he would still race a full schedule.
Hinault, on the other hand, would be more inclined to be the one who would narrow his focus somewhat onto the TDF because that is the most important race in France. Still, since he would be raised with a much deeper racing heritage and broader racing knowledge than US riders, he would no doubt be riding Paris-Nice, French classics, possibly French Cup races, etc..., ie a fuller schedule.
It is quite possible that Italy has never produced a great TDF champion because they have a more insular attitude towards racing. Coppi was a great rider, but his focus was never on the TDF like French riders Anquetil and Hinault.
In America, modern racing fans have had their heads turned towards European racing by Lemond and his TDF wins. This is where their focus has remained, so it is not particularly surprising that that is where Lance's focus is. Who even knows or remembers the unheard of, jaw dropping victory by Lemond when he won the Junior World Championship? How many Lance fans know about his World Championship victory? It is hardly ever mentioned. Who here has heard of American Michael Hiltner and knows of his successful racing in Italy in the 60's? He never won the TDF.
Riders like Bettini, Zabel, Freire, Boogerd, Garzelli, Jalabert, and on and on prove that even though they are rich beyond need, they will still race a full schedule of races, even though their status and bargaining power would no doubt allow them to get by with much less. Even Cipollini wanted to do a full schedule, even though he is a highly specialized talent.
In many ways I think Lance is only doing what he has to do to satisfy his ideas of what success as a bike racer means to him. Nothing wrong with that on the surface, but it does make him appear somewhat one dimensional, even though he is not(IMHO), and leaves him open to what I think is perfectly understandable criticism, considering it's sources.