Well, you bring up a good point. Problem with passing hashes to say, something like functions, is when you misslpell variables/keys, you wind up with a maintenance issue. so when you write a function like,

add(-number1=>10,-nuber2=>0),

you get a right result, but not the right way. Granted, this is the easist bug to bring out, try adding 5 and 3 to get 0. But when you do it with more complex scenarios, you can get really weird software bugs. Also, it makes it harder to refactor code, when you wish to remove parameters, add them or make different requirements, 'cuz when they get called, they may not break.. unless you check for every old parameter and new one in your functions. Yuck. Just a rant :)