Because the post-Tony closings on Broadway have begun. According to the Yahoo! a number of shows will be closing in the coming weeks.
"Pirate Queen" closes this weekend. "Talk Radio" and "LoveMusik" also both end Sunday.
"Radio Golf" and the revival of "Company" both close on July 1.
July 8th says goodbye to "Inherit the Wind" while we turn the A/C on "110 in the Shade" as it closes on July 29th the same day we say goodbye to "Beauty and the Beast" after 13 years.
If you get to Broadway before the end of August you'll be able to catch "Frost/Nixon", "The Year of Magical Thinking" or "Deuce" before they close that month.