If you look at doubles historically (which I have an annoying tendency to do), thru the 60's and 70's it was played by the same players as the singles draw. It was an addendum. Not much attention was paid to it because there was no need to pay extra attention to maintain it. In the 70s as tennis, and specifically singles, became more popular and more profitable, and singles became more of a baseliner's game, singles players stopped playing doubles that much. But even into the 80s some singles players played both, McEnroe and Stephan Edberg were two notable ones, but most didn't. Every once in awhile (Mac the US Open one year) a player will have an especially draining singles run and pull out of the doubles to save energy.
As the singles players played less doubles it has become populated with NCAA players. To me NCAA players are very talented players who didn't have the talent to go pro and went to school instead. They played 4 years and by the time they graduate they are too old to really make a dent in singles. But since doubles is an integral part of the NCAA matches they are all competent doubles players and, just to get into the draws, start playing doubles. Guys like Jim Grabb, Rick Leach and Patrick McEnroe are all examples of this.
But as the singles players have shorn doubles, there is now two separate sets of players to take care of for the tournaments. And tournaments really take care of their players. Hotel suites, car service, parties, free goodies (swag), and so on. Now they can't get away with swag and service for a 64 player draw plus maybe 10 or so other doubles types. They have a 64 player draw for singles and a 64 player (32 team) draw for doubles. Now we're talking about 128 players to take care of rather than maybe 70.
Because of the lack of marketing, and the scheduling (putting the doubles matches at the end of a long day of singles, so people, tired of watching tennis, go home as it starts. Or putting doubles on obscure courts) doubles doesn't draw flies. Tournaments are tired of paying the freight and consider the doubles specialist players free loaders and to some extent they are. But the two biggest culprits are the tournaments and the media. There is very little push to popularize doubles as a sport. It's not an event it's an after thought.
As I said before changing the rules for doubles as they've done only serves to make it seem even more of a second class citizen. The idea behind the rule changes were to entice more singles (marquee) players to enter into the doubles events (now doubles matches won’t last as long, read: they can be gotten over with quicker so we can get on with the more important stuff). But they aren't going to do so unless there is a benefit to do so (such as Roddick playing doubles as preparation for Wimbledon).
To me the only way to save doubles as a pro event (and I do think it needs saving, as I think it's on it's way to extinction), is to go the other direction. Make the doubles part of the tournament as enticing as the singles. Schedule doubles on marquee courts, and as first class matches rather than 'let's see if we can get this in before dark' matches. Put it on display. Don't change doubles scoring, and match play rules, make them the same as singles, on par with singles. Make doubles points count towards rankings. Not just doubles rankings, tennis rankings. Maybe keep track of singles and doubles separately, but the polls that count should incorporate both.
As annoying as the Jenson brothers were (and they were and are annoying), they went a long way towards marketing doubles. The Bryan brothers are less dynamic, but almost as heavily marketed. The marketing is there. But until the tournaments treat the doubles with respect, and media won't, and we will continue to see doubles matches begin as the fans are walking to their cars to go home.(sorry, old tennis nerd with long memory rambling again...... )