Perfect games becoming less common now

On Saturday night, Philadelphia Phillies starting pitcher, Roy Halladay, made history by being the 20th pitcher in Major League Baseball history to throw a perfect game. Halladay achieved this coveted milestone against the Florida Marlins by going 27 up and 27 down, 11 of those by the way of the K. This is the second perfect game this season, Dallas Braden of the Oakland Athletics throwing the first one on May 9th against the Tampa Bay Rays. We already have a no-hitter and two perfect games this season and its not even June yet. I think the perfect game is starting to lose its value.
As much as I like the fact that it was Halladay that tossed a perfect game, I am very displeased of how often a perfect game has occurred in recent years. The first perfect game ever recorded was Lee Richmond in June 12, 1880 which the Worchester Ruby Legs defeated the Cleveland Blues 1-0. Five days later was John Montgomery Ward of the Providence Grays defeating the Buffalo Bisons 5-0. There have been 18 perfect games in the modern century, four of them in the last six seasons (Randy Johnson in 2004, Mark Buehrle in 2009, Braden and Halladay this season).
The longest separation between perfect games was Charlie Robertson in 1922 to Don Larson in 1956. Basically since then a perfect game happens every four-seven years. What is happening here? Are the pitchers getting better? Are the hitters getting worse? It could be possible that the pitchers are much stronger now between their strict diets and lifting weights. Before the 1970's, baseball players never lifted weights, but they were still excellent baseball players. Jim Rice, last year's Hall of Fame inductee, said that he never lifted weights and he hit over 400 homeruns. Maybe baseball just needs to allow pitchers to smoke cigarettes and chew tobacco during games, then hitters can have a better chance. It could also be possible that it is a coincidence, but how much of a coincidence?
It could also be because of the implementation of video and scouting reports. Starting pitchers have four and five days between each start to work on their mechanics, study their opponents and how their can exploit their opponent's weaknesses. Why does a perfect game not happen more often? Because hitters also study their mechanics and the opposing starting pitcher and how their can expose their weaknesses. I honestly don't believe or even don't want to believe that current baseball players are better than players from half a century ago. I just think today's players care so much about improving their game so they can get a big pay-day. It just makes me sad that it is happening more often than it should. As a fan, there is nothing I can do about it but watch the game and probably complain about it right after wards. Who is going to be the next person to join the perfect game club and when is it going to happen?