People like an excuse to just let loose for a day.  Some would say that the Irish shouldn't have been as open as they are on St. Patrick's Day at the turn of the century (damn gingers!), but eventually the public at large got over it.

It's a normal part of the process.  The parades, as goofy and perhaps embarassing as they are, wear down on bigotry.  After awhile, they stop being shocking, and people who grew up with such things begin to wonder why their parents freaked out about them.

As a total geek, I can relate.  When I was growing up in the '80s, Geraldo Rivera and Phil Donohue were kind enough to suggest that Dungeons & Dragons turned kids into cult killers.  There were kids on my block that weren't allowed to play role-playing games because they were demonic in nature.  Going to conventions was like a total catharsis in not having to hide my preferences.

Now, in a startling turn of culture, gamer references show up on shows like The Colbert Report or even some mainstream shows like The X-Files with fair frequency.

It's unfortunate that gays haven't had so easy a transition.