admired doesn't mean popular.
in germany we have the same with dirk nowitzki. everyone is saying "wow he is one of the best basketbal players ever bla bla" but there are not going to be any screaming teenagers when he shows up.
(well not a lot)
in fact the germans won't even watch his games in TV. they will just read about his wins in the newpaper and say like "cool, he won again".
I think the same is true with tennis stars like nadal or fed. everyone has great respect for them and acknowledges their greatness but people are not going to get crazy like they do for a soccer match.
when there is a soccer WC people will not talk about or watch anything else for a month. they will go to public viewing parties and cry if their team loses.
that is just not going to happen in tennis. a few will watch some matches, maybe even have a short talk about the final match but you can absolutely not compare that to the craze about soccer or american football.
federer makes a lot of money because tennis has a very consistent followership all over the world. but in no country in the world (even in switzerland were skiing and even football are certainly more in the media then tennis) there will be a collective craze like there is in soccer.