Although I don't argue with the fact that the financial picture needs to (continue to) make sense, not sure if the comparison with other sports makes sense
If the sport's flagship events are too difficult for the sport's stars to compete in all of them, then clearly something is wrong. The extreme difficulty of the Vuelta is exactly the kind of thing I'm talking about.
The relevance of the comparison with tennis is that tennis has pitched the level of difficulty more appropriately: if they made the grand slams three weeks long and the matches best of nine sets, you might well start to see the big names targeting individual events rather than competing in all of them.
In tennis, you often have players who (due to the heavy calendar in the last decade) get injured/are too fatigued and have to let grand slams slide (e.g. Murray, Nadal, S. Williams often - have to - do it), so not all Grand Slams are always the battle of the best players
In basketball, often US players prefer not to go to the World Championships (and comparable) tournaments, because of the gruesome NBA season. Actually often players (need to) rest during the season (San Antonio Spurs is the best example here) and mostly all NBA teams rest their best players in the last week(s) of the competition, so often you have "top-matches" that are seriously weakened because of top-players not playing. And here as well, it often happens that good players get injured during play-offs ("their GTs") partly because of their body wearing down due to the hard season.
In football, you have the "international team competition" (FIFA Club World Cup) which is a joke, since the Champion's league winner should be hands-down the best team (with the winner of the Copa Libertadores as "closest" team), but the European team often doesn't bother that much and the other teams are much more motivated. So many times here the winner of the "Tour de France" (Champion's League) often doesn't bother with (and doesn't win) this "Vuelta".
Then again, in snooker, most tournaments have a relatively small number of best-of-games (e.g. 11), while only(?) the World's require much more winning frames.
So this would be a "make the Tour de France the hardest one" comparison.
Personally I like watching all 3 GTs (as I also like watching 1-day races like Tour of Flanders and Paris Roubaix) and I don't mind that other names get a shot at "the other GTs", it's especially interesting for the younger guys (in latest years Quintana, Betancur, Majka, Aru) who have a better shot at getting a top 10 GC and for them to get some time to grow.
...I am always willing to see how shorter GTs would be
(but personally I fear a bit that taking away 1 week would eat most into the break-away/medium-mountain stages which are often very nice to see as well)